WO2024051602A1 - Middle frame of mobile terminal, mobile terminal, and preparation method for middle frame - Google Patents

Abstract

The present application relates to the technical field of terminals, in particular to a middle frame of a mobile terminal, a mobile terminal, and a preparation method for the middle frame. The middle frame of the mobile terminal comprises a metal body and a protective layer for wrapping the metal body, wherein an inner side of the metal main body is used for accommodating elements of the mobile terminal, and the protective layer is provided with a hollowed-out portion to expose part of the metal body, and the exposed metal body forms an electricity-leading region; and a conductive anti-corrosion layer is provided on a surface of the electricity-leading region. In the present application, the conductive anti-corrosion layer is arranged at the electricity-leading region of the middle frame of the mobile terminal, such that the electricity-leading region can conduct electricity and has a good corrosion resistance, which improves the reliability of the middle frame.

Description

Middle frame of mobile terminal, mobile terminal and preparation method of middle frame

Cross-references to related applications

This application requires the priority of the Chinese patent application submitted to the China Patent Office on September 9, 2022, with the application number 202211102132.6 and the application name "Middle frame of mobile terminal, mobile terminal and method for preparing middle frame", and its entire content incorporated herein by reference.

Technical field

The present application relates to the field of terminal technology, and in particular, to a middle frame of a mobile terminal, a mobile terminal and a method for preparing the middle frame.

Background technique

Magnesium alloy has good stability and is lightweight. In order to achieve lightweight products, many mobile terminal devices use magnesium alloy as the middle frame. Among them, an exposed metal area needs to be provided on the middle frame to meet the needs of electrostatic discharge (ESD) detection. However, the exposed metal is easily corroded, which will affect the reliability of the middle frame. . The present application provides a middle frame of a mobile terminal, a mobile terminal and a preparation method of the middle frame, so as to improve the corrosion resistance of the conductive area of the middle frame and improve the reliability of the middle frame.

Contents of the invention

The present application provides a middle frame of a mobile terminal, a mobile terminal and a preparation method of the middle frame, so as to improve the corrosion resistance of the conductive area of the middle frame and improve the reliability of the middle frame.

In a first aspect, this application provides a middle frame for a mobile terminal, where the mobile terminal can be a mobile phone, a notebook computer, a tablet computer or a wearable device. The middle frame of the mobile terminal may include a metal body and a protective layer. The protective layer wraps the metal body. The inside of the metal body may be used to accommodate components of the mobile terminal, and a hollow part may be provided on the protective layer to protect the The metal body wrapped by the layer is partially exposed, and the exposed part of the metal body can form a conductive area. This conductive area is used to make the electrostatic charge reach the conductive area first when conducting electrostatic detection on the mobile terminal to avoid components in the mobile terminal. Wounded. In order to ensure that the conductive area is not corroded, a conductive anti-corrosion layer can be provided on the surface of the conductive area. The conductive anti-corrosion layer can not only make the conductive area conductive, but also prevent the conductive area from being corroded, ensuring that Mid-frame reliability.

Among them, the protective layer is a plastic protective layer.

Specifically, a plurality of openings can be provided on the side wall of the middle frame, and the hollow portion can be located on the inner wall of the opening, so that the conductive area is formed on the inner wall of the opening, and the conductive area can also be provided on the inner wall of the middle frame. In other locations, as long as the ESD electrostatic detection is performed on the mobile terminal with the above-mentioned middle frame, the electrostatic charge can be made to reach the electrification area first to avoid components being damaged. The following example takes the electrification area being set on the inner wall of the opening as an example. Be explained:

When the conductive area is disposed on the inner wall of the opening, the conductive anti-corrosion layer is also disposed on the inner wall of the opening, and the side of the conductive anti-corrosion layer away from the conductive area does not protrude from the hollow portion to ensure that the card holder and the universal string When components such as the universal serial bus (USB for short), earphones, and side buttons are matched with the openings, the conductive anti-corrosion layer will not hinder components such as the card tray, USB, earphones, and side buttons, ensuring that the side buttons, USB, earphones, etc. and the normal use of components such as the card tray.

In a possible embodiment, in order to ensure that the conductive anti-corrosion layer provided on the conductive area does not protrude from the side of the hollow portion away from the metal body, a depression can be provided on the surface of the conductive area. When, the surface of the recessed portion is the above-mentioned conductive area, the conductive anti-corrosion layer can be at least partially disposed in the recessed portion, and the conductive anti-corrosion layer covers the conductive area, wherein, in order to facilitate the arrangement, the conductive area is formed at the bottom of the recessed portion, The conductive anti-corrosion layer is arranged on the side of the conductive area away from the bottom of the recessed part, and the conductive anti-corrosion layer does not protrude from the recessed part, so as to ensure that the conductive anti-corrosion layer is set and does not cause the occurrence of card trays and side keys that match the openings. put one's oar in.

When specifically arranging the conductive anti-corrosion layer, the conductive anti-corrosion layer can be in the same plane as the inner wall of the opening, the conductive anti-corrosion layer can be located in the recess, or the side of the conductive anti-corrosion layer away from the conductive area can be located in the protective layer.

When the above-mentioned conductive anti-corrosion layer is specifically arranged, the conductive anti-corrosion layer may include at least two conductive anti-corrosion sub-layers arranged in a stack, and the standard electrode potential of each conductive anti-corrosion sub-layer is from the direction away from the conductive area to the direction close to the conductive area. Decrease in sequence. Among them, the conductive anti-corrosion sub-layer on the side far away from the conductive area can be directly electrically connected to other structures for detection; while the standard electrode potential value of the conductive anti-corrosion sub-layer far away from the conductive area is larger, This means that the metal of the conductive anti-corrosion sub-layer is less reactive and is not easily corroded.

Specifically, the conductive anti-corrosion layer may include a first conductive anti-corrosion sub-layer and a second conductive anti-corrosion sub-layer, wherein the first conductive anti-corrosion sub-layer and the second conductive anti-corrosion sub-layer can be stacked, and the side of the first conductive anti-corrosion sub-layer away from the second conductive anti-corrosion sub-layer corresponds to the conductive area, that is, the first conductive anti-corrosion sub-layer and the conductive area are also stacked. Wherein, the first conductive anti-corrosion sub-layer may include one or more of aluminum, titanium, zinc, nickel or molybdenum, and the second conductive anti-corrosion sub-layer may include one of copper or lead. The copper layer and the lead layer have good stability, so that the second conductive anti-corrosion sub-layer has good corrosion resistance, and the copper does not affect the electrical connectivity, making it easy to detect.

In the above embodiment, in order to improve the electrical connection performance between the first conductive anti-corrosion sub-layer and the second conductive anti-corrosion sub-layer, the impedance between the first conductive anti-corrosion sub-layer and the second conductive anti-corrosion sub-layer may be set to less than 1Ω, the resistance impedance between the first conductive anti-corrosion sub-layer and the middle frame is also less than 1Ω, which can be understood as the impedance between any two metals in the metal body is less than 1Ω. Specifically, the impedance between any two metals in the metal body can be 0.6Ω, 0.5Ω or 0.8Ω.

In the above implementation, the middle frame may include a metal material that is not corrosion-resistant. Specifically, the metal body may be a magnesium-aluminum alloy body, a magnesium-lithium alloy body, or a magnesium-silicon alloy body.

In a second aspect, the present application also provides a method for preparing the middle frame in any of the technical solutions of the first aspect, by coating a shielding layer on the surface of the middle frame; and etching a part of the shielding layer on the middle frame. Corrosion is performed to form a conductive area; a conductive anti-corrosion layer is formed on the surface of the conductive area through a composite deposition process; the remaining shielding layer on the middle frame is removed, thereby forming a middle frame with a conductive anti-corrosion layer.

Wherein, the step of etching part of the shielding layer on the side of the middle frame to form the conductive area may include various forms, such as: using a laser engraving process to etch the shielding layer at the opening on the side wall of the middle frame. Etching is performed locally to form a recessed portion on the surface of the metal body, and the conductive region is formed on the surface of the recessed portion. Or, the partial position of the shielding layer at the opening of the side wall of the middle frame is etched through a laser engraving process, so that part of the metal body is exposed, and the exposed metal body forms a conductive area.

Specifically, when the shielding layer is etched through the laser engraving process, the size deviation is small, and workpieces with relatively complex shapes can be processed. That is, the openings on the side walls of the middle frame can be blocked through the laser engraving process. The layers are processed, wherein the openings on the side walls of the middle frame can be USB holes, side button installation holes, card tray holes, etc.

In a possible embodiment, the above-mentioned composite deposition process includes spraying, electroplating, chemical plating or electrochemical plating, and which process is specifically used can be adjusted according to actual needs.

In a third aspect, a mobile terminal includes the middle frame in any of the technical solutions of the first aspect, and also includes a display screen, a back shell, side buttons and a card holder. The middle frame has a first side and a second side arranged oppositely. , wherein the display screen is set on the first side of the middle frame, the back shell is set on the second side of the middle frame, the number of side buttons can be more than one, and the side buttons, USB, headphones and card tray are respectively set on different sides of the middle frame. in the opening. Since the conductive anti-corrosion layer provided in the opening on the middle frame has a conductive anti-corrosion layer, the conductive anti-corrosion layer can be prevented from being corroded, and the conductive anti-corrosion layer does not protrude from the surface of the inner wall of the opening, preventing the conductive anti-corrosion layer from mating with the opening. interference with the card tray and side buttons to ensure the normal use of side buttons, USB, headphones, card trays and other components.

Description of the drawings

Figure 1 is a schematic structural diagram of a mobile terminal provided by an embodiment of the present application;

Figure 2 is a partial cross-sectional view of a mobile terminal provided by an embodiment of the present application;

Figure 3 is a partial cross-sectional view without a conductive anti-corrosion layer provided at the opening of the middle frame of the mobile terminal provided by the embodiment of the present application;

Figure 4 is a partial cross-sectional view of a conductive anti-corrosion layer provided at the opening of the middle frame of the mobile terminal provided by the embodiment of the present application;

Figure 5 is a schematic structural diagram of a middle frame of a mobile terminal provided by an embodiment of the present application;

Figure 6 is a partial enlarged view of A in Figure 5;

Figure 7 is another partial cross-sectional view without a conductive anti-corrosion layer provided at the opening of the middle frame of the mobile terminal provided by the embodiment of the present application;

Figure 8 is another partial cross-sectional view of a conductive anti-corrosion layer provided at the opening of the middle frame of the mobile terminal provided by the embodiment of the present application;

Figure 9 is a mid-frame preparation process for a mobile mid-end provided by an embodiment of the present application;

Figures 10a to 10d show the process diagram of making the middle frame in the embodiment of the present application.

Reference signs:

1-middle frame; 2-side buttons; 10-opening; 11-conducting area; 12-recessed part; 101-metal body; 102-protective layer; 103-hollow part; 20-conductive anti-corrosion layer; 21-No. A conductive anti-corrosion sub-layer; 22-a second conductive anti-corrosion sub-layer; 30-shielding layer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be described in further detail below in conjunction with the accompanying drawings.

Referring to Figure 1, a mobile terminal generally includes a middle frame 1, a casing 3 and a display screen 4. The display screen 4 and the casing 3 are arranged on both sides of the middle frame 1. In order to reduce the weight of the mobile terminal, magnesium alloy or lithium alloy can be used. alloy to make the middle frame 1 of the mobile terminal. Specifically, it can be made by extruding profiles, The middle frame 1 is produced by die-casting, casting or metal injection molding (MIM) process. More specifically, when the middle frame 1 is specifically set, the middle frame 1 is provided with openings 10 for matching other components, such as: openings for matching multiple side buttons, openings for matching the card tray, and openings for matching. Openings for connecting USB, etc. When specifically setting the openings, in order to meet the needs of ESD detection of the middle frame, the metal body of the magnesium alloy or lithium alloy on the inner wall of the middle frame needs to be exposed on the inner wall of the opening of the middle frame 1. However, the magnesium and lithium elements in magnesium alloys and lithium alloys are relatively active in nature and are easily corroded and damaged, which will affect the normal use of the side keys and the card holder.

In view of this, the present application provides a new middle frame of a mobile terminal, which solves the above problems by providing a conductive anti-corrosion layer where the opening is provided in the middle frame.

The terminology used in the following examples is for the purpose of describing specific embodiments only and is not intended to limit the application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "said", "above", "the" and "the" are intended to also Expressions such as "one or more" are included unless the context clearly indicates otherwise.

Reference in this specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Therefore, the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in other embodiments", etc. appearing in different places in this specification are not necessarily References are made to the same embodiment, but rather to "one or more but not all embodiments" unless specifically stated otherwise. The terms “including,” “includes,” “having,” and variations thereof all mean “including but not limited to,” unless otherwise specifically emphasized.

The middle frame of the mobile terminal provided by the embodiment of the present application can be applied to the mobile terminal, where the mobile terminal can be a mobile phone, a tablet computer, a wearable device, a notebook computer, etc. When the middle frame is used in a mobile terminal, continuing to refer to Figure 1, the display screen 4 and the housing 3 of the mobile terminal can be respectively disposed on the first and second sides of the middle frame 1, that is, the middle frame 1 can be used as a display screen. 4 and the support structure of the casing 3. In addition, the opening 10 on the middle frame 1 can be used to cooperate with the side keys 2 and card holders included in the mobile terminal. Referring to FIG. 2 , the inner space of the middle frame 1 is used to accommodate components on the mobile terminal. The middle frame 1 may include a metal body and a protective layer covering the surface of the metal body 101 . Part of the metal body in the middle frame 1 is exposed. The exposed metal body part can be used for static electricity detection. The exposed metal body part forms a conductive area. Specifically, the conductive area can be set in the opening 10 on the middle frame 1. Moreover, a conductive anti-corrosion layer 20 can also be provided at the conductive area, which can prevent the conductive area from being corroded and ensure the normal use of components such as the card holder and the side button 2. Among them, the conductive anti-corrosion layer 20 does not protrude from the surface of the inner wall of the opening 10, which can prevent the conductive anti-corrosion layer 20 from obstructing the card holder and the side key 2 that cooperate with the opening, so as to ensure that the conductive anti-corrosion layer 20 will not be set Affecting the normal operation of components such as the card tray and side buttons.

Referring to Figures 3 and 4, the middle frame 1 of the mobile terminal can include a metal body 101 and a protective layer 102. The protective layer 102 can wrap the metal body 101. The inside of the metal body 101 can be used to accommodate components of the mobile terminal, and in The portion of the protective layer 102 located outside the component can be provided with a hollow portion 103 so that the metal body 101 wrapped by the protective layer 102 is at least partially exposed. The exposed portion of the metal body 101 can form a conductive area 11, and the conductive area 11 is made of For conducting ESD detection on mobile terminals, in order to ensure that the conductive area 11 is not corroded, a conductive anti-corrosion layer 20 can be provided on the surface of the conductive area 11. The conductive anti-corrosion layer 20 can make the conductive area 11 conductive. function, it can also prevent the conductive area 11 from being corroded and ensure the reliability of the middle frame.

Referring to Figures 3, 4, 5 and 6, the metal body 101 in the middle frame of the mobile terminal can be a metal body that is easily corroded, such as a magnesium-aluminum alloy body, a magnesium-lithium alloy body, or a magnesium-silicon alloy body. The sides of the middle frame 1 There may be a plurality of openings 10 on the wall, and a conductive area 11 is formed on the inner wall of the opening 10 (the conductive area 11 is the part of the metal body 101 exposed to the outside, that is, on the protective layer 102 of the middle frame 1 With a hollow portion 103), this electrification area is used to allow the electrostatic charge to reach the electrification area 11 first when performing ESD detection on the mobile terminal, so as to prevent components in the mobile terminal from being damaged. In order to ensure that the conductive area 11 can work stably and continuously, a conductive anti-corrosion layer 20 can be provided on the surface of the conductive area 11. The arrangement of the conductive anti-corrosion layer 20 can ensure the conductive performance of the conductive area 11 itself and can also prevent conduction. The electrical area 11 is corroded, thereby ensuring the stability of the middle frame 1; the provision of the conductive anti-corrosion layer 20 can ensure the normal use of components such as the card tray, USB, earphones, and side buttons that cooperate with the opening 10 of the middle frame 1.

Among them, when the conductive anti-corrosion layer 20 is specifically set, the conductive anti-corrosion layer 20 does not protrude from the surface of the inner wall of the opening 10 to ensure that after the installation of the conductive anti-corrosion layer 20 is completed, it will not interfere with the use of components such as the card tray and side keys. .

Referring to Figures 7 and 8, in the above embodiment, when specifically forming the conductive area 11, a recessed portion 12 can be provided on the surface of the exposed metal body 101, wherein the surface of the recessed portion 12 can also be exposed. The metal body 101, that is, the bottom surface of the recessed portion 12 can also form the above-mentioned conductive area 11, the conductive anti-corrosion layer 20 can be at least partially disposed in the recessed portion 12, and when the conductive anti-corrosion layer 20 is provided, the conductive anti-corrosion layer 20 can lead to The electric area 11 is covered to ensure that the conductive area 11 is not corroded. More specifically, the conductive area 11 can be formed at the bottom of the recessed portion 12 , the conductive anti-corrosion layer 20 is provided on a side of the conductive area 11 away from the bottom of the recessed portion 12 , and at least part of the conductive anti-corrosion layer is provided in the recessed portion 12 20, as long as the side of the conductive anti-corrosion layer 20 away from the conductive area 11 does not protrude from the inner wall of the opening, it can be understood that the thickness of the conductive anti-corrosion layer 20 can be smaller than the depth of the recessed portion 12, or the conductive anti-corrosion layer The thickness of 20 is less than the sum of the depth of the recessed portion 12 and the height of the hollow portion.

For example, the surface of the conductive anti-corrosion layer 20 can be in the same plane as the surface of the inner wall of the opening 10 , or the conductive anti-corrosion layer 20 can also be in the same plane. All are located in the recessed portion 12 to ensure that components such as the card holder and side keys that cooperate with the opening 10 will not interfere with the middle frame.

Continuing to refer to FIGS. 7 and 8 , the above-mentioned conductive anti-corrosion layer 20 may include at least two conductive anti-corrosion sub-layers, wherein a plurality of conductive anti-corrosion sub-layers are arranged sequentially in a direction away from the conductive area 11 , and two adjacent conductive anti-corrosion sub-layers are In the sub-layer, the standard electrode potential of the conductive anti-corrosion sub-layer close to the conductive area 11 is less than the standard electrode potential of the conductive anti-corrosion sub-layer far away from the conductive area 11, and the standard electrode potential of the conductive area 11 is less than that of the conductive anti-corrosion sub-layer. The standard electrode potential of the adjacent conductive anti-corrosion sub-layer, that is, the standard electrode potential of the conductive anti-corrosion sub-layer far away from the conductive area 11 is larger, indicating that the metal activity of the conductive anti-corrosion sub-layer far away from the conductive area 11 is smaller and not Easily corroded.

In a possible implementation, the conductive anti-corrosion layer may include only two layers, that is, the conductive anti-corrosion layer 20 includes a first conductive anti-corrosion sub-layer 21 and a second conductive anti-corrosion sub-layer 22, where the first conductive anti-corrosion sub-layer 21 is provided. On the surface of the conductive area 11, the second conductive anti-corrosion sub-layer 22 is provided on the side of the first conductive anti-corrosion sub-layer 21 away from the conductive area 11, wherein the first conductive anti-corrosion sub-layer 21 can be aluminum, titanium, One or more of zinc, nickel or molybdenum, and the second conductive anti-corrosion sub-layer 22 can be one of copper or lead. The copper layer and the lead layer have good stability, so that the second conductive anti-corrosion sub-layer 22 has good corrosion resistance, and the copper does not affect the electrical connectivity, which facilitates detection.

Specifically, the first conductive anti-corrosion sub-layer 21 can be made of aluminum, and the second conductive anti-corrosion sub-layer 22 can be a copper layer. Copper has relatively good corrosion resistance and is conductive. The aluminum layer is disposed between the copper layer and the lead. Between the electric areas, it can prevent the potential difference between the copper layer and the conductive area 11 from being too large, causing a galvanic reaction, thereby accelerating corrosion.

In the above embodiment, in order to improve the electrical connection performance between the first conductive anti-corrosion sub-layer 21 and the second conductive anti-corrosion sub-layer 22, the impedance between the first conductive anti-corrosion sub-layer 21 and the second conductive anti-corrosion sub-layer 22 is It can be set to less than 1Ω, and the resistance impedance between the first conductive anti-corrosion sub-layer 21 and the middle frame 1 is also less than 1Ω. It can be understood that the impedance between any two metals in the middle frame is less than 1Ω.

Based on the same technical concept, this application provides a method for preparing the above-mentioned middle frame. Please refer to Figure 9. Figure 9 shows the preparation process of the middle frame of the mobile terminal in the embodiment of the application. Figures 10a to 10d show A schematic diagram of the manufacturing process of the middle frame in the embodiment of the present application is provided, which may specifically include the following steps:

S201: Coat the shielding layer 30 on the surface of the middle frame 1;

Figure 10a is a partial schematic diagram of the shielding layer 30 provided on the middle frame 1 in the embodiment of the present application. When specifically implementing the above step S201, the shielding layer 30 on the surface of the middle frame 1 can be, but is not limited to, setting a mask on the surface of the middle frame 1 board, or a coating such as ink is provided on the surface of the middle frame 1 .

S202: Etch part of the shielding layer 30 on the middle frame to form the conductive area 11;

Referring to Figure 10b, the shielding layer 30 is etched, specifically through a laser engraving process. The shielding layer 30 can be etched at the side wall opening of the middle frame 1 or at other locations to form the conductive area 11. The specific position of the conductive area is not limited here. During the etching process, only part of the main body in the middle frame 1 can be exposed, or part of the main body surface can be etched to form a recess 12 on the surface of the main body. The conductive area 11 is formed on the surface of the recessed portion 12 .

The laser engraving process can be used to control the size deviation of the conductive area 11 to about 0.1 mm, and the conductive area 11 with a relatively complex shape can be processed through the laser engraving process.

S203: Form a conductive anti-corrosion layer on the surface of the conductive area 11 through a composite deposition process;

Please refer to Figure 10c. The composite deposition process includes spraying, electroplating, chemical plating or electrochemical plating. The specific process used can be adjusted according to actual needs. Specifically, the conductive anti-corrosion layer may include a first conductive anti-corrosion sub-layer 21 and a second conductive anti-corrosion sub-layer 22. The first conductive anti-corrosion sub-layer 21 may be formed on the surface of the conductive area 11 using a sputtering process. Then, a second conductive anti-corrosion sub-layer 22 is formed by sputtering on the surface of the first conductive anti-corrosion sub-layer 21, thereby forming a conductive anti-corrosion layer; of course, the conductive anti-corrosion layer can also include a third conductive anti-corrosion sub-layer, a fourth conductive anti-corrosion sub-layer, etc. By analogy, the conductive anti-corrosion layer can be formed in multiple layers based on processes such as spraying, electroplating, electroless plating or electrochemical plating. Here, only two layers are taken as an example.

The conductive anti-corrosion sub-layer formed on the surface of the conductive area 11 by the above-mentioned spray plating process has a large surface adhesion, which can improve the adhesion between two adjacent conductive anti-corrosion sub-layers and prevent the two adjacent conductive anti-corrosion sub-layers from being damaged. Detachment between preservative sub-layers. Specifically, the surface roughness of the conductive anti-corrosion sub-layer formed by spraying is large, and the adhesion force is generally greater than or equal to 4B.

S204: Remove the remaining occlusion layer 30 on the middle frame.

Please refer to Figure 10d. After removing the shielding layer 30 in other areas of the middle frame 1, a first conductive anti-corrosion sub-layer 21 and a second conductive anti-corrosion sub-layer 22 can be formed on the surface of the conductive area 11 to prevent the conductive area 11 from is corroded, and the conductive area 11 also has a conductive function, which is beneficial to improving the stability of the middle frame 1 .

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, and all of them should be covered. within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (12)

1. A middle frame of a mobile terminal, characterized in that the middle frame includes a metal body and a protective layer, the protective layer is used to wrap the metal body, and the inside of the metal body is used to accommodate components of the mobile terminal, The protective layer is provided with a hollow portion so that part of the metal body is exposed, and the exposed metal body forms a conductive area. The conductive area is used to prevent electrostatic charges from being detected first when electrostatic detection is performed on the mobile terminal. Arrive at the electrification zone;

   Wherein, a conductive anti-corrosion layer is provided on the surface of the conductive area.
2. The middle frame according to claim 1, wherein the side wall of the middle frame has a plurality of openings, and the hollow portion is located on the inner wall of the opening, so that the inner wall of the opening has the A conductive area, wherein the side of the conductive anti-corrosion layer located on the conductive area away from the conductive area does not protrude from the hollow portion.
3. The middle frame according to claim 2, wherein the surface of the conductive area has a recessed portion, and at least part of the conductive anti-corrosion layer is disposed in the recessed portion.
4. The middle frame according to claim 1, wherein the conductive anti-corrosion layer includes at least two stacked conductive anti-corrosion sub-layers, each of which is arranged in a direction from the direction away from the conductive area to the direction close to the conductive area. The standard electrode potential of the conductive anti-corrosion sub-layer decreases sequentially.
5. The middle frame according to claim 4, wherein the conductive anti-corrosion layer includes a first conductive anti-corrosion sub-layer and a second conductive anti-corrosion sub-layer, and the second conductive anti-corrosion sub-layer is disposed on the first conductive anti-corrosion sub-layer. a first side of the sublayer facing away from the conductive region;

   Wherein, the first conductive anti-corrosion sub-layer includes one or more of aluminum, titanium, zinc, nickel or molybdenum, and the second conductive anti-corrosion sub-layer includes one of copper or lead.
6. The middle frame according to claim 5, wherein the resistance impedance between the metal body and the first conductive anti-corrosion sub-layer is less than 1Ω, and the resistance between the second conductive anti-corrosion sub-layer and the first conductive anti-corrosion sub-layer is The resistive impedance between sublayers is less than 1Ω.
7. The middle frame according to any one of claims 1 to 6, characterized in that the metal body includes a corrosion-resistant metal material.
8. The middle frame according to claim 7, wherein the metal body includes a magnesium-aluminum alloy body, a magnesium-lithium alloy body, or a magnesium-silicon alloy body.
9. A preparation method for preparing the middle frame of the mobile terminal according to any one of claims 1 to 8, characterized in that it includes:

   Apply a blocking layer to the surface of the middle frame;

   Etch part of the shielding layer on the middle frame to form a conductive area;

   A conductive anti-corrosion layer is formed on the surface of the conductive area through a composite deposition process;

   Remove the remaining occlusion layer on the middle frame.
10. The preparation method according to claim 9, characterized in that the composite deposition process includes spraying, electroplating, chemical plating or electrochemical plating.
11. The preparation method according to claim 9, characterized in that the step of etching part of the shielding layer on the middle frame to form a conductive area includes:

    The shielding layer at the opening of the side wall of the middle frame is etched through a laser engraving process so that a depression is formed on the surface of the metal body, The conductive area is formed on the surface of the recessed portion.
12. A mobile terminal, characterized by comprising a middle frame according to any one of claims 1 to 8.