End processing method of aluminum conductive part and aluminum conductive part

Abstract

The invention discloses an end processing method of an aluminum conductive part and the aluminum conductive part. Stamping the end part of the aluminum conductive piece to obtain a flat end, forming a first transition layer on the inner surface of the cavity of the copper cap connecting piece or the flat end, and installing the copper cap connecting piece on the flat end to obtain an assembly end; and punching the assembly end to obtain a mounting hole, forming a second transition layer on the outer surface of the copper connection terminal or the inner surface of the mounting hole, and mounting the copper connection terminal in the mounting hole. And the first transition layer and the second transition layer are respectively and independently selected from silver, titanium, tin or nickel. By processing the end of the aluminum conductive piece, the copper cap connecting piece increases the contact area between the aluminum end and copper, reduces the contact resistance, reduces the heat loss, and improves the efficiency and reliability; by applying the transition layer between the copper and the aluminum, the potential difference is reduced, electrochemical corrosion is prevented, the reliability of connection between the copper and the aluminum is improved, the resistance is reduced, and local heating is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of processing conductive parts for new energy electric vehicles, and more specifically, to a method for processing the end of an aluminum conductive part and an aluminum conductive part. Background Art

[0002] Conductive parts are components with a relatively large cost in the high-voltage connector harness of electric vehicles. The traditionally used conductor materials are mainly copper and copper alloys. Copper has good electrical and mechanical properties and is an ideal material for electrical conduction. Against the background of the development of charging power towards high-power charging, the current charging technology standard has increased the maximum allowable charging current to 800A, and it will further develop towards 1000A and higher in the future. Without adding cooling measures at the vehicle end, when the current increases, according to Joule's law (Q = I 2 Rt), it is necessary to reduce the conductor resistance to prevent problems such as thermal failure of the vehicle. An effective measure to reduce resistance is to increase the conductor cross-sectional area. Generally, the maximum current-carrying capacity of a 120mm 2 copper cable is 500A. To obtain a higher current-carrying capacity, the cross-sectional area of the cable needs to be larger than 120mm 2 This large size will cause problems such as overweight wire harness quality and too large bending radius. Therefore, based on the requirements of new energy vehicles for lightweight, cost control, and energy efficiency, aluminum conductive parts are widely used due to their light weight, low cost, and good electrical conductivity.

[0003] In electric vehicles, aluminum conductive parts and copper conductive parts are applied to different parts due to their respective characteristics. For example, aluminum bars are used in the in-vehicle charging circuit to reduce weight. If the end of the aluminum bar needs to be frequently plugged and unplugged or needs to carry a high current, copper needs to be welded to ensure high electrical conductivity, so as to achieve the lightweight, high-efficiency conductivity, and overall performance of the conductive part. However, when copper and aluminum are connected, on the one hand, due to the large potential difference between copper and aluminum, it is easy to form a micro-battery effect in a humid air environment, which is easy to form electrochemical corrosion and reduce the reliability of the connection structure. On the other hand, the potential difference between copper and aluminum forms a relatively large resistance, which is easy to cause local heating under the action of current and has potential safety hazards. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a method for processing the end of an aluminum conductive part and an aluminum conductive part, so as to solve the safety problems caused by electrochemical corrosion and large resistance caused by the large potential difference between copper and aluminum.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] Provide an aluminum conductive part;

[0007] Perform stamping treatment on the end of the aluminum conductive part to obtain a flat end;

[0008] Provide a copper cap connector, the copper cap connector having a cavity into which the flat end can be inserted, and forming a first transition layer on the inner surface of the cavity or on the flat end, and installing the copper cap connector onto the flat end to obtain an assembled end;

[0009] Drill a hole in the assembled end to obtain a mounting hole;

[0010] Provide a copper connection terminal, form a second transition layer on the outer surface of the copper connection terminal or on the inner surface of the mounting hole, and install the copper connection terminal into the mounting hole;

[0011] Wherein, the materials of the first transition layer and the second transition layer are independently selected from silver, titanium, tin or nickel respectively.

[0012] The present invention also provides an aluminum conductive member, comprising:

[0013] A flat end;

[0014] A copper cap connector, the copper cap connector having a cavity into which the flat end can be inserted, the flat end being inserted into the cavity, and the copper cap connector being welded to the flat end;

[0015] A first transition layer, the first transition layer being located between the inner surface of the cavity and the flat end, and the first transition layer connecting the copper cap connector and the flat end;

[0016] A copper connection terminal, the aluminum conductive member further having a mounting hole, the mounting hole penetrating through the flat end and the copper cap connector along the thickness direction of the flat end, the copper connection terminal being installed in the mounting hole, and the copper connection terminal being welded to the copper cap and the flat end;

[0017] A second transition layer, the second transition layer being located between the inner surface of the mounting hole and the copper connection terminal, and the second transition layer connecting the copper connection terminal with the flat end and the copper cap connector.

[0018] Implementing the embodiments of the present invention will have the following beneficial effects:

[0019] On the one hand, the end treatment method of the aluminum conductive member provided by the embodiments of the present invention increases the contact area between the aluminum end and the copper by using a copper cap connector, reduces the contact resistance, reduces heat loss, and improves efficiency and reliability; by applying a transition layer (i.e., the first transition layer and the second transition layer) between copper and aluminum, the potential difference is reduced, electrochemical corrosion is prevented, the reliability of the connection between copper and aluminum is improved, and the resistance is reduced to avoid local heating.

[0020] In another aspect, in the aluminum conductive member provided by the embodiment of the present invention, a copper cap connector is sleeved outside the flat end, and a copper connection terminal is arranged in the installation hole penetrating through both of them. By arranging a first transition layer between the flat end and the copper cap connector, and a second transition layer between the flat end, the copper cap connector and the copper connection terminal, the first transition layer and the second transition layer block the direct contact between aluminum and copper, reduce the potential difference, prevent electrochemical corrosion, and improve the conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Among them:

[0023] Figure 1 is a flowchart of a method for processing the end of an aluminum conductive member provided by an embodiment of the present invention.

[0024] Figure 2 is a sectional view of an aluminum conductive member provided by an embodiment of the present invention.

[0025] Figure 3 is a three-view drawing of a copper cap connector provided by an embodiment of the present invention, where Figure 3 A is a front view of the copper cap connector, Figure 3 B is a top view of the copper cap connector, Figure 3 C is a left view of the copper cap connector.

[0026] Figure 4 is a three-view drawing of an aluminum conductive member provided by an embodiment of the present invention, Figure 4 A is a front view of the aluminum conductive member, Figure 4 B is a top view of the aluminum conductive member, Figure 4 C is a left view of the aluminum conductive member. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] Refer to Figure 1 , an embodiment of the present invention provides a method for processing the end of an aluminum conductive member, including the following processes:

[0029] 1) Provide an aluminum conductive part.

[0030] 2) Stamp the end of the aluminum conductive part to obtain a flat end.

[0031] 3) Provide a copper cap connector. The copper cap connector has a cavity into which the flat end can be inserted. A first transition layer is formed on the inner surface of the cavity or on the flat end, and the copper cap connector is installed on the flat end to obtain an assembled end.

[0032] 4) Drill a hole in the assembled end to obtain a mounting hole.

[0033] 5) Provide a copper connection terminal. A second transition layer is formed on the outer surface of the copper connection terminal or on the inner surface of the mounting hole, and the copper connection terminal is installed in the mounting hole.

[0034] Wherein, the materials of the first transition layer and the second transition layer are independently selected from silver, titanium, tin or nickel respectively.

[0035] Optionally, the above-mentioned end treatment is performed at both ends of the aluminum conductive part, or the above-mentioned end treatment is performed at one end of the aluminum conductive part, and other end treatment methods are performed at the other end, such as welding a soft connection terminal to the end of the aluminum conductive part in the prior art to adapt to the installation tolerance, and the soft connection terminal is formed by diffusion welding of multiple layers of copper foil.

[0036] Specifically, the aluminum conductive part is an aluminum busbar or an aluminum rod. The copper connection terminal is a copper ring or a copper column. The copper ring is used to connect with an external copper electrical connector through a bolt, and the copper column is used to plug into an external copper electrical connector. The copper cap connector increases the contact area between the aluminum end and copper, reduces the contact resistance, reduces heat loss, and improves efficiency and reliability. However, the copper cap connector, the copper connection terminal and the aluminum conductive part are still welded with dissimilar metals, and there is also an electrochemical corrosion problem to a certain extent.

[0037] The present invention further forms a first transition layer on the inner surface of the copper cap cavity or on the flat end of the aluminum conductive part, and forms a second transition layer on the outer surface of the copper connection terminal or on the inner surface of the mounting hole of the assembled end. The materials of the first transition layer and the second transition layer are independently selected from silver, titanium, tin or nickel respectively. The first transition layer and the second transition layer are used to block the direct contact between aluminum and copper, reduce the potential difference, prevent electrochemical corrosion, improve the reliability of the connection between copper and aluminum, and reduce the resistance to avoid local heating.

[0038] Furthermore, the thickness of the first transition layer is 0.8 μm to 6 μm, and the thickness of the second transition layer is 0.8 μm to 6 μm. If the transition layer is too thin, it may not be able to effectively block, and if the transition layer is too thick, it may increase the resistance or affect the mechanical properties.

[0039] In some alternative embodiments, the first transition layer and the second transition layer are formed by vacuum evaporation.

[0040] It should be noted that, compared with the magnetron sputtering method, the equipment cost of magnetron sputtering is high and the process is complex. Compared with the electroplating method, the electroplating method requires chemical solutions, which are prone to environmental pollution problems and the risk of uneven plating. Vacuum evaporation is to heat the metal to evaporate it in a high-vacuum environment and then deposit it into a film on the substrate. The vacuum evaporation method can obtain a high-purity, good bonding force, and uniform coating.

[0041] Preferably, a first transition layer is formed on the inner surface of the cavity of the copper cap connector, and a second transition layer is formed on the outer surface of the copper connection terminal, which is convenient for production operations. Further, the copper cap connector and the copper connection terminal are directly subjected to vacuum evaporation, a first transition layer is formed on the inner and outer surfaces of the copper cap connector, and a second transition layer is formed on the inner and outer surfaces of the copper connection terminal. The first transition layer on the outer surface of the copper cap connector and the second transition layer on the inner surface of the copper connection terminal can further play an anti-oxidation role.

[0042] Exemplarily, the process of forming the first transition layer and the second transition layer includes: placing the copper cap connector and the copper connection terminal in a vacuum coating device respectively, placing the metal particles to be evaporated, and the metal particles obtain energy and are converted into gas and deposited on the first copper connector and the second copper connector to form a metal transition layer. The background vacuum degree of the vacuum coating device is 1.0×10 -5 Torr~1.0×10 -6 Torr, and the deposition rates of the first transition layer and the second transition layer are 0.3nm / s~1.5nm / s respectively.

[0043] In some alternative embodiments, the first transition layer and the second transition layer are respectively density-graded transition layers, and the density of the density-graded transition layer gradually increases in the direction from the aluminum material to the copper material.

[0044] Optionally, the density-graded transition layer includes at least two density layers, which can be two layers, three layers, four layers or other multi-layer density layers to achieve density grading.

[0045] Further, the density-graded transition layer includes a first density layer and a second density layer. The first density layer is close to the copper material, and the second density layer is close to the aluminum material; the density of the first density layer is greater than that of the second density layer.

[0046] It should be noted that the compactness of the first density layer and the second density layer affects the interface bonding strength, electrical conductivity and mechanical properties. The vacuum evaporation method can control the density of the first density layer and the second density layer by controlling the deposition rate.

[0047] Exemplarily, when the first density layer and the second density layer are nickel transition layers, the lattice structures and physical properties of copper and nickel (such as the coefficient of thermal expansion) are relatively close. The dense nickel layer can better bond with copper, reduce the interface resistance, and ensure good electrical conductivity; copper has high electrical conductivity and mechanical strength, and the dense nickel layer can ensure the stability of current transmission and the reliability of mechanical connection. The lattice structures and physical properties of aluminum and nickel are quite different, and the sparse nickel layer can better adapt to the thermal expansion and mechanical deformation of aluminum; the sparse nickel layer can also reduce the interfacial stress concentration and avoid cracks or peeling caused by the mismatch of the coefficient of thermal expansion.

[0048] When the deposition rate is low, atoms have enough time to migrate on the substrate surface to form a more ordered and compact structure, thus improving the density. While at high deposition rates, atoms accumulate rapidly and have insufficient migration time, easily forming a porous or columnar structure, resulting in a decrease in density.

[0049] Furthermore, the deposition rate of the second transition layer is greater than that of the first transition layer. Preferably, the deposition rate of the first transition layer is 0.1 nm / s to 0.8 nm / s, and the deposition rate of the second transition layer is 0.9 nm / s to 3.0 nm / s.

[0050] Furthermore, the thickness of the first density layer is 0.4 μm to 3 μm, and the thickness of the second density layer is 0.4 μm to 3 μm. Preferably, the thickness of the first transition layer is 0.8 μm to 1.2 μm, and the thickness of the second transition layer is 1.2 μm to 1.8 μm. The first transition layer is thin and dense, avoiding brittle fracture caused by excessive thickness; the second transition layer is thick and slightly sparse, which can match the coefficient of thermal expansion of aluminum, and the porous structure can absorb the welding residual stress, thereby improving the connection stability of the copper transition connector.

[0051] In some alternative embodiments, during the process of forming the assembly end, it further includes: performing a first welding connection between the copper cap connector and the flat end, and the first welding is polymer diffusion welding, ultrasonic welding, friction stir welding, or brazing.

[0052] After installing the copper connection terminal in the installation hole, it further includes: performing a second welding connection between the copper connection terminal and the assembly end, and the second welding is polymer diffusion welding, ultrasonic welding, friction stir welding, or brazing.

[0053] Furthermore, the first welding and the second welding can be carried out step by step or synchronously. By welding the contact surfaces of the transition layer with aluminum or copper through the first welding and / or the second welding, not only the welding strength is improved, but also the welding quality of the welding interface between the transition layer and copper or aluminum is improved.

[0054] In some alternative embodiments, the aluminum conductive member includes a conductor core and an insulating layer covering the conductor core. Before the punching and stamping process, it further includes: circumferentially cutting the insulating layer, removing the end insulating layer to obtain an exposed end, and performing stamping treatment on the exposed end.

[0055] Furthermore, the aluminum conductive member further includes an armor layer covering the conductor core and the insulating layer. Before circumferentially cutting the insulating layer, it further includes: circumferentially cutting the armor layer, removing the end armor layer to obtain an exposed insulating end, and circumferentially cutting the insulating layer of the exposed insulating end.

[0056] Combined Figures 2 to 4 , the aluminum conductive member provided by the embodiment of the present invention is obtained through the above-mentioned end treatment method. The aluminum conductive member includes a flat end 1, a copper cap connector 2, a copper connection terminal 3, a first transition layer 4, and a second transition layer 5.

[0057] The copper cap connector 2 has a cavity into which the flat end 1 can be inserted. The flat end 1 is inserted into the cavity, and the copper cap connector 2 is welded to the flat end 1. The first transition layer 4 is located between the inner surface of the cavity and the flat end 1, and the first transition layer 4 connects the copper cap connector 2 and the flat end 1.

[0058] The aluminum conductive member is also provided with a mounting hole that penetrates through the flat end 1 and the copper cap connector 2 along the thickness direction of the flat end 1. The copper connection terminal 3 is installed in the mounting hole, and the copper connection terminal 3 is welded to the copper cap connector 2 and the flat end 1. The second transition layer 5 is located between the inner surface of the mounting hole and the copper connection terminal 3, and the second transition layer 5 connects the copper connection terminal 3 with the flat end 1 and the copper cap connector 2.

[0059] It should be noted that the flat end 1 and the copper cap connector 2 form a composite end. The mounting hole penetrates through the composite end. The copper connection terminal 3 and the second transition layer 5 are located in the mounting hole, and the second transition layer 5 connects the copper connection terminal 3 with the composite end.

[0060] Specifically, the aluminum conductive member is suitable for connecting a charging socket and a battery pack in an electric vehicle. The aluminum conductive member includes a conductive main body 10 connected to the flat end 1. The conductive main body 10 can be preformed into an adapted bent shape according to the installation space, which helps the conductive main body 10 to be accommodated in the environment of a vehicle with limited space through bent arrangement. Further, the aluminum conductive member includes a conductor core and an insulating layer covering the conductor core, or the aluminum conductive member further includes an armor layer covering the conductor core and the insulating layer. The conductor core includes the conductive main body 10 connected to the flat end 1. The copper connection terminal 3 can be a copper ring or a copper post. Figure 2 Only the copper connection terminal 3 being a copper ring is taken as an example in

[0061] It can be understood that the aluminum conductive part provided in this embodiment is sleeved with a copper cap connector 2 on the flat end 1, and a copper connection terminal 3 is arranged in the installation hole passing through both of them. By arranging a first transition layer 4 between the flat end 1 and the copper cap connector 2, and a second transition layer 5 between the flat end 1, the copper cap connector 2 and the copper connection terminal 3, the first transition layer 4 and the second transition layer 5 block the direct contact between aluminum and copper, reduce the potential difference, prevent electrochemical corrosion, and improve the conductivity.

[0062] In some optional embodiments, the thickness of the first transition layer 4 is 0.8 μm to 6 μm; the thickness of the second transition layer 5 is 0.8 μm to 6 μm. If the transition layer is too thin, it may not be able to effectively block; if the transition layer is too thick, it may increase the resistance or affect the mechanical properties.

[0063] Furthermore, the first transition layer 4 and the second transition layer 5 are respectively density-graded transition layers, and the density of the density-graded transition layer gradually increases in the direction from the aluminum material to the copper material. Optionally, the first transition layer 4 and the second transition layer 5 are respectively density-graded transition layers formed by vacuum evaporation.

[0064] Optionally, the first transition layer 4 and the second transition layer 5 respectively include at least two density layers, which can be two layers, three layers, four layers or other multiple density layers to achieve density grading.

[0065] Exemplarily, the first transition layer 4 includes a first density layer and a second density layer, the density of the first density layer is greater than that of the second density layer, and the copper cap connector 2, the first density layer, the second density layer, and the flat end 1 are connected in sequence. Exemplarily, the metal transition layer is a nickel transition layer. The lattice structures and physical properties (such as the thermal expansion coefficient) of copper and nickel are relatively close. The first density layer is a dense nickel layer, and the dense nickel layer can better bond with copper, reduce the interface resistance, and ensure good conductivity; copper has high conductivity and mechanical strength, and the dense nickel layer can ensure the stability of current transmission and the reliability of mechanical connection. The lattice structures and physical properties of aluminum and nickel are quite different, and the sparse nickel layer can better adapt to the thermal expansion and mechanical deformation of aluminum; the first density layer is a sparse nickel layer, and the sparse nickel layer can also reduce the interface stress concentration and avoid cracks or peeling caused by the mismatch of thermal expansion coefficients.

[0066] The following are specific embodiments:

[0067] Embodiment 1

[0068] (1) Provide an aluminum conductive bar, and perform stamping treatment on the end of the aluminum conductive bar to obtain a flat end.

[0069] (2) Provide a copper cap connector, perform vacuum evaporation on the surface of the copper cap connector at a deposition rate of 0.1 nm / s to obtain a first nickel transition layer with a thickness of 0.8 μm, and install the copper cap connector onto the flat end to obtain an assembled end.

[0070] (3) Drill a hole in the assembled end to obtain an installation hole.

[0071] (4) Provide a copper ring, also perform vacuum evaporation on the surface of the copper cap connector at a deposition rate of 0.1 nm / s to obtain a second nickel transition layer with a thickness of 0.8 μm, and install the copper ring into the installation hole.

[0072] (5) Ultrasonically weld the copper cap connector, the copper ring and the aluminum busbar.

[0073] Example 2

[0074] (1) Provide an aluminum busbar, perform stamping on the end of the aluminum busbar to obtain a flat end.

[0075] (2) Provide a copper cap connector, perform vacuum evaporation on the surface of the copper cap connector at a deposition rate of 2 nm / s to obtain a first nickel transition layer with a thickness of 6 μm, and install the copper cap connector onto the flat end to obtain an assembled end.

[0076] (3) Drill a hole in the assembled end to obtain an installation hole.

[0077] (4) Provide a copper ring, also perform vacuum evaporation on the surface of the copper cap connector at a deposition rate of 2 nm / s to obtain a second nickel transition layer with a thickness of 6 μm, and install the copper ring into the installation hole.

[0078] (5) Ultrasonically weld the copper cap connector, the copper ring and the aluminum busbar.

[0079] Example 3

[0080] (1) Provide an aluminum busbar, perform stamping on the end of the aluminum busbar to obtain a flat end.

[0081] (2) Provide a copper cap connector, perform the first vacuum evaporation on the surface of the copper cap connector at a deposition rate of 0.1 nm / s to obtain a first density layer with a thickness of 0.4 μm, then perform the second vacuum evaporation at a deposition rate of 0.9 nm / s to obtain a second density layer with a thickness of 0.4 μm again, and further obtain a first nickel transition layer with a thickness of 0.8 μm and the density of the first density layer is greater than that of the second density layer; then install the copper cap connector onto the flat end to obtain an assembled end.

[0082] (3) Drill a hole in the assembled end to obtain an installation hole.

[0083] (4) Provide a copper ring, and perform vacuum evaporation coating twice on the surface of the copper ring. The deposition rate of the first vacuum evaporation coating is 0.1 nm / s, obtaining a third density layer with a thickness of 0.4 μm. Then, perform the second vacuum evaporation coating with a deposition rate of 0.9 nm / s, obtaining a fourth density layer with a thickness of 0.4 μm again, and further obtaining a second nickel transition layer with a thickness of 0.8 μm. Then, install the copper ring into the mounting hole.

[0084] (5) Ultrasonically weld the copper cap connector, the copper ring, and the aluminum conductive bar.

[0085] Comparative Example 1

[0086] The difference between Comparative Example 1 and Example 1 is only that the copper cap connector is not provided, and the copper ring is installed after drilling holes at the ends of the aluminum conductive bar.

[0087] Comparative Example 2

[0088] The difference between Comparative Example 2 and Example 1 is that nickel plating is not performed on the surfaces of the copper cap connector and the copper ring.

[0089] Comparative Example 3

[0090] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the first nickel transition layer and the second nickel transition layer are nickel sheets with a thickness of 0.1 mm respectively.

[0091] Test Example

[0092] After processing the aluminum conductive parts in Examples 1 to 3 and Comparative Examples 1 to 3, the conductivity is tested by the four-probe method, and the test results are shown in the following table.

[0093] Conductivity Table of Aluminum Conductive Parts in Examples 1 to 3 and Comparative Examples 1 to 3

[0094] Conductivity (%IACS) Example 1 60.7 Example 2 60.5 Example 3 61.1 Comparative Example 1 60.4 Comparative Example 2 57.3 Comparative Example 3 54.7

[0095] Result Explanation:

[0096] Examples 1 to 3 all have relatively high conductivity. In Comparative Example 1, the conductivity is 60.4% IACS. Since the copper cap connector is not provided for the aluminum conductive part in Comparative Example 1, the copper cap connector in Example 1 increases the contact area between the aluminum end and copper, reduces the contact resistance, and thus improves the conductivity.

[0097] Among them, the conductivity of Example 1 is 60.7% IACS, the conductivity of Example 2 is 60.5% IACS, and the conductivity of Example 3 is 61.1% IACS. In Example 3, nickel transition layers with decreasing density are sequentially formed on the surfaces of the copper cap connector and the copper ring. The dense nickel layer can better bond with copper, reducing the interfacial resistance and ensuring good conductivity. The sparse nickel layer can better adapt to the thermal expansion and mechanical deformation of aluminum, reducing the interfacial stress concentration. Compared with Example 1, the conductivity of Example 3 is improved.

[0098] In Comparative Example 2, the conductivity is 57.3% IACS. Since nickel is not plated on the surfaces of the copper cap connector and the copper ring in Comparative Example 2, when welding dissimilar copper-aluminum materials, the potential difference is large, the resistance at the interface increases, and the conductivity decreases.

[0099] In Comparative Example 3, the conductivity is 54.7% IACS. The main purpose of setting a nickel transition layer between copper and aluminum is to reduce galvanic corrosion, improve the bonding performance, and alleviate the problems caused by the difference in thermal expansion coefficients. However, in Comparative Example 3, the nickel sheet is too thick, increasing the interfacial stress. The excessively thick nickel layer causes interlayer peeling or cracking due to the accumulation of thermal stress during temperature changes, and the decrease in bonding strength leads to a decrease in conductivity. Therefore, the conductivity of Example 1 is better than that of Comparative Example 3.

[0100] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for end treatment of an aluminum conductive part, characterized in that, It includes the following processes: Provide an aluminum conductive part; Perform stamping on the end of the aluminum conductive part to obtain a flat end; Provide a copper cap connector, the copper cap connector has a cavity for the flat end to be inserted into, form a first transition layer on the inner surface of the cavity or on the flat end, and install the copper cap connector onto the flat end to obtain an assembled end; Drill holes in the assembled end to obtain mounting holes; Provide a copper connection terminal, form a second transition layer on the outer surface of the copper connection terminal or on the inner surface of the mounting hole, and install the copper connection terminal into the mounting hole; Wherein, the materials of the first transition layer and the second transition layer are independently selected from silver, titanium, tin or nickel respectively.

2. The end treatment method of the aluminum conductive part according to claim 1, characterized in that, The first transition layer and the second transition layer are formed by vacuum evaporation.

3. The end treatment method of the aluminum conductive part according to claim 2, characterized in that, The first transition layer and the second transition layer are respectively density-graded transition layers, and the density of the density-graded transition layer gradually increases in the direction from the aluminum material to the copper material.

4. The end treatment method of the aluminum conductive part according to claim 3, characterized in that, The density-graded transition layer includes a first density layer and a second density layer, the first density layer is close to the copper material, and the second density layer is close to the aluminum material; The density of the first density layer is greater than that of the second density layer.

5. The end treatment method of the aluminum conductive part according to claim 4, characterized in that, The deposition rate of the second density layer is greater than that of the first density layer; the deposition rate of the first density layer is 0.1 nm / s to 0.8 nm / s, and the deposition rate of the second density layer is 0.9 nm / s to 3.0 nm / s; The thickness of the first density layer is 0.4 μm to 3 μm, and the thickness of the second density layer is 0.4 μm to 3 μm.

6. The end treatment method of the aluminum conductive part according to any one of claims 2 to 4, characterized in that, The thickness of the first transition layer is 0.8 μm to 6 μm; the thickness of the second transition layer is 0.8 μm to 6 μm.

7. The end treatment method of the aluminum conductive part according to any one of claims 1 to 5, characterized in that, During the process of forming the assembled end, it further includes: performing a first welding connection between the copper cap connector and the flat end, and the first welding is polymer diffusion welding, ultrasonic welding, friction stir welding or brazing; After installing the copper connection terminal into the mounting hole, it further includes: performing a second welding connection between the copper connection terminal and the assembled end, and the second welding is polymer diffusion welding, ultrasonic welding, friction stir welding or brazing.

8. An aluminum conductive part, characterized in that, It includes: A flat end; A copper cap connector, the copper cap connector has a cavity for the flat end to be inserted into, the flat end is inserted into the cavity, and the copper cap connector is welded to the flat end; A first transition layer, the first transition layer is located between the inner surface of the cavity and the flat end, and the first transition layer connects the copper cap connector and the flat end; A copper connection terminal, the aluminum conductive part is further provided with a mounting hole, the mounting hole penetrates through the flat end and the copper cap connector along the thickness direction of the flat end, the copper connection terminal is installed in the mounting hole, and the copper connection terminal is welded to the copper cap and the flat end; A second transition layer, the second transition layer is located between the inner surface of the mounting hole and the copper connection terminal, and the second transition layer connects the copper connection terminal with the flat end and the copper cap connector.

9. The aluminum conductive part according to claim 8, wherein, The thickness of the first transition layer is 0.8 μm to 6 μm; the thickness of the second transition layer is 0.8 μm to 6 μm.

10. The aluminum conductive part according to any one of claims 8 to 9, characterized in that, The first transition layer and the second transition layer are respectively density-gradient transition layers, and the density of the density-gradient transition layer gradually increases in the direction from the aluminum material to the copper material.

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