A copper-aluminum material connecting method, a copper-aluminum composite base material and a wire harness

Abstract

The application provides a copper-aluminum material connecting method, a copper-aluminum composite base material and a wire harness. The copper-aluminum material connecting method comprises the following steps: S100, superimposing a to-be-connected part of a copper material and a to-be-connected part of an aluminum material; S200, simultaneously applying pressure to the to-be-connected part of the copper material and the to-be-connected part of the aluminum material until a preset pressure is reached; S300, maintaining the preset pressure, and simultaneously applying a preset temperature to the to-be-connected part of the copper material and the to-be-connected part of the aluminum material and maintaining the preset temperature for a preset time, so as to perform high-molecular diffusion welding on the to-be-connected part of the copper material and the to-be-connected part of the aluminum material, and form a metal key connection between contact surfaces of the to-be-connected part of the copper material and the to-be-connected part of the aluminum material. The application adopts the method of high-molecular diffusion welding, realizes the metal key connection between the copper and the aluminum, has small conductivity loss at a welding position, and is not prone to electrochemical corrosion at the welding position.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dissimilar metal welding, in particular to a copper-aluminum material connecting method, a copper-aluminum composite base material and a wire harness. BACKGROUND

[0002] With the rapid development of new energy vehicles, vehicle weight reduction is imminent. The quality change and connection reliability of the wire harness, as an important part of the vehicle, affect the development and safety of new energy vehicles. Traditional copper wire harness has been difficult to meet the requirements of lightweight vehicles. The use of aluminum material with electrical conductivity second only to copper and density close to one-third of copper to replace part of the copper material helps to reduce the weight of the vehicle, but this involves the problem of copper-aluminum dissimilar metal connection.

[0003] Due to the large electrode potential difference between copper and aluminum, if directly connected, electrochemical corrosion will occur between copper and aluminum, and aluminum is easy to be corroded, resulting in increased resistance in the connection area, which will have serious consequences in electrical connection. The current copper-aluminum connection methods are generally fusion welding, friction welding, ultrasonic welding, cold pressure welding, electron beam welding and explosive welding. These welding methods have large joint brittleness, are easy to produce pores and cracks in the weld, and produce electrochemical corrosion. SUMMARY

[0004] The present application provides a copper-aluminum material connecting method, a copper-aluminum composite base material and a wire harness to solve the problems of large joint brittleness, easy to produce pores and cracks in the weld, and electrochemical corrosion existing in the current copper-aluminum connection method.

[0005] Embodiments of the first aspect of the present application propose a copper-aluminum material connecting method for connecting copper material and aluminum material to be connected. The copper-aluminum material connecting method comprises: step S100, superimposing the copper material to be connected part and the aluminum material to be connected part; step S200, simultaneously applying pressure to the copper material to be connected part and the aluminum material to be connected part until a preset pressure is reached; step S300, maintaining the preset pressure, and simultaneously applying a preset temperature to the copper material to be connected part and the aluminum material to be connected part and maintaining for a preset time, to perform high polymer diffusion welding on the copper material to be connected part and the aluminum material to be connected part, so as to form a metal bond connection between the contact surfaces of the copper material to be connected part and the aluminum material to be connected part.

[0006] In some embodiments, the preset temperature is less than or equal to the solid phase transition temperature of the aluminum material, and greater than or equal to the softening temperature of the aluminum material.

[0007] In some embodiments, the preset temperature is 460℃-600℃, the preset pressure is 1Mpa-15Mpa, and the preset time is 1s-1000s.

[0008] In some embodiments, the preset temperature is 460-550℃, the preset pressure is 3-11 MPa, and the preset time is 6-60 s.

[0009] In some embodiments, the copper material is copper or copper alloy, and the aluminum material is aluminum or aluminum alloy.

[0010] In some embodiments, the copper material is copper bar, copper foil, copper braid, copper wire, or flexible flat cable, and the aluminum material is aluminum bar, aluminum foil, aluminum braid, aluminum wire, or aluminum braid.

[0011] In some embodiments, in the step S100, an intermediate layer is arranged between the to-be-connected part of the copper material and the to-be-connected part of the aluminum material, and the material of the intermediate layer comprises at least one of a brazing agent, zinc, silver, nickel, magnesium, and silicon.

[0012] In some embodiments, the material of the intermediate layer further comprises at least one of copper and aluminum.

[0013] In some embodiments, the intermediate layer is a soldering sheet, liquid solder, foil, electroplated layer, sprayed layer, or vapor deposition layer.

[0014] In some embodiments, in the step S100, the surface of the to-be-connected part of the aluminum material is provided with an oxidation-preventing protective layer.

[0015] In some embodiments, the oxidation-preventing protective layer is a zinc layer or a copper-zinc alloy layer.

[0016] In some embodiments, the copper-aluminum material connecting method further comprises, before the step S100, a step of cleaning the to-be-connected surface of the copper material and the to-be-connected surface of the aluminum material.

[0017] Embodiments of the second aspect of the application provide a copper-aluminum composite substrate connected by the copper-aluminum material connecting method according to the first aspect.

[0018] Embodiments of the third aspect of the application provide a wire harness comprising a copper conductor and an aluminum conductor, which are connected according to the copper-aluminum material connecting method of the first aspect.

[0019] In some embodiments, the wire harness is an automobile wire harness.

[0020] The features and advantages of the application include:

[0021] 1. The application adopts a high polymer diffusion welding method, simultaneously applies pressure to the copper material to be connected and the aluminum material to be connected until a preset pressure is reached, then maintains the preset pressure and simultaneously applies a preset temperature to the copper material to be connected and the aluminum material to be connected and maintains the preset temperature for a preset time, realizes the metal bond connection between copper and aluminum, the conductivity loss of the welded part is small, the welded part is not prone to electrochemical corrosion, and the problems of existing copper-aluminum connection methods, such as large brittleness of the welded joint, easy production of pores and cracks in the weld, and electrochemical corrosion, are solved.

[0022] 2. The copper-aluminum material connection method of the application can improve the effect of metal bond connection by controlling the welding temperature, pressure and time at 460-600 DEG C, 1-15 MPa and 1-1000 s respectively.

[0023] 3. The copper-aluminum material connection method of the application can improve the welding performance of copper and aluminum by setting an intermediate layer between the copper material and the aluminum material, on the one hand, the aluminum oxide layer on the welding surface can be destroyed, and on the other hand, the formation of copper-aluminum intermetallic compound can be reduced.

[0024] 4. The copper-aluminum composite substrate of the application is welded by a high polymer diffusion welding method, a metal bond connection is formed between the copper material and the aluminum material, the conductivity loss of the welded part is small, the welded part is not prone to electrochemical corrosion, and the problems of existing copper-aluminum connection structure, such as large brittleness of the welded joint, easy production of pores and cracks in the weld, and electrochemical corrosion, are solved.

[0025] 5. The wire harness of the application uses aluminum conductors to replace part of the copper conductors, compared with the existing copper wire harness, the quality is smaller, which helps to reduce the overall vehicle quality.

[0026] 6. The copper conductor and the aluminum conductor of the wire harness of the application are welded by a high polymer diffusion welding method, a metal bond connection is formed between the copper conductor and the aluminum conductor, the conductivity loss of the welded part is small, the welded part is not prone to electrochemical corrosion, and the safety and reliability of driving are improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] The following drawings are only intended to illustrate and explain the application, and do not limit the scope of the application. Among them:

[0028] Figure 1 is a flowchart of the copper-aluminum material connection method of an embodiment of the application;

[0029] Figure 2 is a structural schematic diagram of the copper-aluminum composite substrate of the first embodiment of the application;

[0030] Figure 3 is a structural schematic diagram of the copper-aluminum composite substrate of the second embodiment of the application;

[0031] Figure 4 is a structural schematic diagram of a copper-aluminum composite substrate of a third embodiment of the present application.

[0032] Main element label explanation:

[0033] 1, copper bar; 2, aluminum foil; 3, intermediate layer; 4, aluminum woven tape; 5, FFC; 6, aluminum bar. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described with reference to the accompanying drawings.

[0035] As shown in Figure 1 the first aspect of the present application provides a copper-aluminum material connecting method for connecting copper material and aluminum material to be connected, the copper-aluminum material connecting method comprising:

[0036] Step S100: superimposing the connecting part of the copper material and the connecting part of the aluminum material;

[0037] Step S200: simultaneously applying pressure to the connecting part of the copper material and the connecting part of the aluminum material until a preset pressure is reached, and the connecting part of the copper material and the connecting part of the aluminum material are not heated during this process;

[0038] Step S300: maintaining the preset pressure, and simultaneously applying a preset temperature to the connecting part of the copper material and the connecting part of the aluminum material and maintaining for a preset time, to perform high molecular diffusion welding on the connecting part of the copper material and the connecting part of the aluminum material, so that the atoms of the contact surfaces of the connecting part of the copper material and the connecting part of the aluminum material diffuse into each other, forming a metal bond connection.

[0039] In step S200, under the action of the preset pressure, the micro convex point contact surfaces of the copper material and the aluminum material are plastically deformed, and the surface oxidation film of the connecting part is crushed in the deformation. In this step, by applying pressure to the connecting part of the copper material and the aluminum material without heating, not only can the oxidation film previously formed on the surface of the copper material and the aluminum material be destroyed, but also new oxidation film can be formed between the copper material and the aluminum material, which is beneficial to the subsequent formation of the metal bond connection.

[0040] In step S300, during the process of applying a preset temperature and a preset pressure to the copper material and the aluminum material and maintaining for a preset time, the connecting part of the copper material and the aluminum material changes as follows:

[0041] In the first stage, under the action of the preset temperature and the preset pressure, a metal bond is formed at the contact position of the clean surfaces of the copper material and the aluminum material, and micro-holes are formed at the non-contact position and remain on the interface; in the second stage, the atoms continue to diffuse, many micro-holes on the interface disappear, the grain boundaries migrate away from the original interface, and part of the small micro-holes remain in the grains; in the third stage, the atoms continue to diffuse until the interface and the micro-holes disappear to form new grain boundaries.

[0042] The copper-aluminum dissimilar metal is welded by the polymer diffusion welding method, the metal bond between the copper and the aluminum is realized, the conductivity loss of the welding position is small, the electrochemical corrosion is not easy to occur at the welding position, and the problems of the existing copper-aluminum connection mode, such as large brittleness of the welded joint, easy generation of pores and cracks in the welding seam, and electrochemical corrosion, are solved.

[0043] The copper-aluminum material connection method can be implemented by means of the existing welding equipment, the welding equipment generally has an upper welding head and a lower welding head, the copper material and the aluminum material to be welded are placed between the upper welding head and the lower welding head, the connection parts of the copper material and the aluminum material are overlapped, the welding equipment is started, and the upper welding head and the lower welding head simultaneously apply the preset temperature and the preset pressure to the connection parts of the copper material and the aluminum material.

[0044] In some embodiments, the preset temperature is less than or equal to the solid phase transition temperature of the aluminum material and greater than or equal to the softening temperature of the aluminum material, which can maximize the atomic activity of the copper-aluminum contact surface, thereby facilitating atomic diffusion to form a metal bond.

[0045] Optionally, the preset temperature is 460-600℃, which can avoid or reduce the generation of copper-aluminum intermetallic compounds and facilitate the mutual diffusion of copper-aluminum atoms to form a metal bond.

[0046] Optionally, the preset pressure is 1-15Mpa, which can destroy the oxide layer on the metal surface and promote the mutual diffusion of copper-aluminum atoms to form a metal bond.

[0047] Optionally, the preset time is 1-1000s, which is also the atomic diffusion time, which can ensure sufficient diffusion between atoms and prevent material softening and deformation, and if the time is too short, the atoms are not fully diffused, and if the time is too long, the material is seriously softened and deformed or even melted.

[0048] The present application realizes the mutual diffusion of intermetallic atoms and the formation of a metal bond by controlling the temperature, pressure and time, and improves the effect of metal bond connection.

[0049] For example, the preset temperature is 460-550℃, the preset pressure is 3-11Mpa, and the preset time is 6-60s, which provides more optimal diffusion conditions for atomic diffusion, enables the copper-aluminum dissimilar metal atoms to be rapidly and well diffused and connected, and further improves the effect of metal bond connection.

[0050] Optionally, the copper material is copper or copper alloy, and the aluminum material is aluminum or aluminum alloy.

[0051] Optionally, the copper material is copper bar, copper foil, copper braided mesh, copper wire or flexible flat cable (FFC), and of course other structural forms of copper material.

[0052] Optionally, the aluminum material is aluminum bar, aluminum foil, aluminum braided mesh, aluminum braided tape or aluminum wire, and of course other structural forms of aluminum material.

[0053] In some embodiments, in step S100, an intermediate layer is provided between the to-be-connected part of the copper material and the to-be-connected part of the aluminum material, and the material of the intermediate layer includes a brazing agent and at least one of zinc, silver, nickel, magnesium and silicon.

[0054] The intermediate layer and the contact surface of the base material (i.e. the copper material and the aluminum material) undergo complex reactions such as atomic diffusion, eutectic, hypoeutectic, eutectoid and hypoeutectoid.

[0055] The intermediate layer can destroy the oxide layer on the surface of copper and aluminum, allowing copper and aluminum atoms to escape better. After the intermediate layer is liquefied by heat, it can fill the micropores on the surface of copper and aluminum, not only inhibiting the generation of the oxide film, but also promoting the connection of metal bonds. In addition, the intermediate layer can increase the surface energy of copper and aluminum, making it easier to exchange atoms. Through the above three mechanisms, the intermediate layer can inhibit the generation of intermetallic compounds between copper and aluminum, thereby significantly improving the welding effect of copper and aluminum. Through experiments, the inventors have verified that the thickness of the copper-aluminum intermetallic compound can be reduced to less than 3 μm by setting the intermediate layer, and even the generation of the copper-aluminum intermetallic compound can be avoided, so that the copper-aluminum material after welding has greater tensile strength and higher mechanical properties.

[0056] Optionally, the melting point of the intermediate layer is lower than the melting point of the copper material and the aluminum material, so that the copper and aluminum soften and melt earlier to fill the micropores on the surface of copper and aluminum.

[0057] Optionally, the material of the intermediate layer further includes at least one of copper and aluminum. Since the prices of zinc, silver, nickel, magnesium and silicon are relatively high, the addition of copper and / or aluminum can reduce the cost.

[0058] Exemplarily, the material of the intermediate layer includes AL-Zn-Cu alloy, which reacts with the contact surface of copper and aluminum to generate Cu-Zn and Al-Zn alloys, and the generated alloys are eutectic or hypoeutectic structures with metal bond, which can improve the metal bond connection effect between copper and aluminum.

[0059] Exemplarily, the material of the intermediate layer comprises an Al-Zn-Mg-Cu alloy, which not only has a lower melting point and can quickly fill the micropores on the surface of the copper-aluminum, but also the Mg contained therein can inhibit the generation of brittle Cu-Zn intermetallic compounds, thereby improving the metal bond connection effect between copper and aluminum.

[0060] Exemplarily, the flux of the intermediate layer can be at least one selected from LiCl, KCl, ZnCl2, NaF, ZnCl, SrCl2, LiF, CaF2, and NaCl.

[0061] Optionally, the intermediate layer is a metal-based soldering sheet, liquid solder, foil, electroplated layer, sprayed layer, or vapor deposition layer. For example, the thickness of the foil can be 0.01 mm to 0.3 mm.

[0062] In order to verify the effects of the intermediate layer, the welding temperature, the welding time, and the welding pressure provided in the present application on the copper-aluminum welding, the inventors conducted 10 groups of experiments. The welding parameters in the experiments include that the welding temperature and the holding temperature are selected from multiple different temperatures in the range of 460°C to 550°C, the welding time and the holding time are selected from multiple different times in the range of 6s to 60s, and the welding pressure is selected from multiple different pressures in the range of 3Mpa to 11Mpa. The serial numbers 1-10 in Table 1 below represent the 1st to 10th groups of experiments, and the specific welding parameters of each group of experiments are shown in Table 1.

[0063] Table 1: Welding of copper material and aluminum material with AL-Zn as the intermediate layer

[0064]

[0065]

[0066] As can be seen from Table 1, the copper material and the aluminum material are welded with AL-Zn as the intermediate layer, 460°C to 550°C as the welding and holding temperature, 6s to 60s as the welding and holding time, and 3Mpa to 11Mpa as the welding pressure, and the peel strength of the welded piece obtained is not less than 650N, which indicates that the welded piece meets the use requirements. As can also be seen from Table 1, when the welding and holding time is equal and the welding pressure is equal, the higher the welding and holding temperature (in the range of 460°C to 550°C), the greater the peel strength of the welded piece obtained, that is, the better the welding effect.

[0067] In some other embodiments, in step S100, the surface of the to-be-connected part of the aluminum material is provided with an anti-oxidation protective layer. On the one hand, the anti-oxidation protective layer can protect the active aluminum from generating an oxide layer, and on the other hand, by providing the anti-oxidation protective layer, there is no need to separately add an intermediate layer, especially no need to add a flux for breaking the oxide layer.

[0068] Exemplarily, the anti-oxidation protective layer is a zinc layer or a copper-zinc alloy layer. For example, the zinc layer or the copper-zinc alloy layer can be formed on the surface of the to-be-connected part of the aluminum material by a gas phase deposition method or an electroplating method.

[0069] In some embodiments, the copper-aluminum material connecting method of the present application further comprises a cleaning treatment step before step S100: cleaning treatment is performed on the to-be-connected surfaces of the copper material and the aluminum material to remove the oxide film and other impurities on the surfaces of the copper and aluminum materials.

[0070] For example, the cleaning method is cleaning: the surfaces of the base materials are polished with sandpaper, the aluminum material and the copper material are respectively immersed in a 10% by mass NaOH solution and a 10% by mass HNO3 solution for 30s, then the aluminum and copper materials are cleaned with alcohol, and then the aluminum and copper materials are dried. Alternatively, the cleaning method is vacuum heating: the organic matter or water vapor adsorption layer is volatilized by vacuum heating (for example, at a temperature of 350°C).

[0071] The present embodiment enables the copper-aluminum material surfaces to be in close contact with each other by pre-treating the copper-aluminum material, and destroys and decomposes the surface contaminants that hinder diffusion, so as to form a metal bond connection.

[0072] In some embodiments, the copper-aluminum material connecting method of the present application further comprises the following step after step S300: the temperature is further increased and the pressure holding time is further prolonged to enable the atoms on the metal surfaces to diffuse sufficiently.

[0073] In some embodiments, the to-be-connected surface of the copper material and the to-be-connected surface of the aluminum material are both located in an anti-oxidation protective gas.

[0074] Since copper and aluminum are both active metals, they will slowly oxidize under the action of air and water, and the oxidation speed will increase when the temperature increases. In the present embodiment, when the to-be-connected surface of the copper material and the to-be-connected surface of the aluminum material are preheated, the increase in temperature will cause the to-be-connected surfaces of the copper material and the aluminum material to be rapidly oxidized, thereby forming copper-aluminum oxides and reducing the mechanical and electrical properties of the copper-aluminum connecting part. Therefore, during the preheating and the entire processing process, the inventors place the to-be-connected surface of the copper material and the to-be-connected surface of the aluminum material in an anti-oxidation protective gas to avoid or reduce the generation of copper-aluminum oxides. Specifically, the anti-oxidation protective gas can be an inert gas or nitrogen.

[0075] In a first specific implementation, as Figure 1 , Figure 2As shown, the copper material is a copper bar 1, the aluminum material is an aluminum foil 2 or an aluminum foil assembly formed by stacking multiple aluminum foils 2, and an intermediate layer 3 is arranged between the to-be-connected part of the copper bar 1 and the to-be-connected part of the aluminum foil 2, i.e., the intermediate layer 3 is arranged between the entire to-be-connected part of the copper bar 1 and the entire to-be-connected part of the aluminum foil 2. By arranging the intermediate layer 3 between the copper bar 1 and the aluminum foil 2, on one hand, the aluminum oxide layer on the welding surface can be damaged, and the contact resistance can be reduced; on the other hand, the formation of copper-aluminum intermetallic compounds can be reduced, thereby improving the welding performance of the two.

[0076] In this embodiment, the copper bar 1 and the single-layer or multi-layer aluminum foil 2 are connected by using the polymer diffusion welding method, atomic interdiffusion is formed between the copper bar 1 and the aluminum foil 2 to form a metal bond, the gap between the dissimilar materials is eliminated, the contact surfaces are tightly connected, and the basic condition for electrochemical reaction is eliminated, thereby preventing electrochemical reaction.

[0077] In this embodiment, further, the preset pressure in step S200 is 1 Mpa-15 Mpa, the preset temperature in step S300 is 460-600 DEG C, and the preset time is 1-1000 s.

[0078] In this embodiment, further, the aluminum material to be connected is a multi-layer aluminum foil 2, and the copper-aluminum material connection method further includes the following step before step S100: step S010: stacking the multi-layer aluminum foil 2 to form an integrated aluminum foil assembly.

[0079] In this embodiment, the copper bar 1 is made of copper or copper alloy, for example, the length of the copper bar 1 is 1-5000 mm, the width is 1-150 mm, and the thickness is 1-20 mm; the aluminum foil 2 is made of aluminum or aluminum alloy, for example, the length of the aluminum foil 2 is 1-5000 mm, the width is 1-150 mm, and the thickness is 0.001-1 mm.

[0080] As shown in FIG. 1, Figure 1 , Figure 3 As shown in the second specific embodiment, the copper material is a copper bar 1, the aluminum material is an aluminum woven tape 4, the preset pressure in step S200 is 1 Mpa-15 Mpa, the preset temperature in step S300 is 460-600 DEG C, the preset time is 1-100 s, and the welding is performed at one time.

[0081] In this embodiment, the polymer diffusion welding method is used to realize the metal bond connection between the copper bar 1 and the aluminum woven tape 4, the conductivity loss at the welding position is small, and electrochemical corrosion is not easy to occur at the welding position.

[0082] In this embodiment, the copper bar 1 is made of copper or copper alloy, for example, the length of the copper bar 1 is 1mm-5000mm, the width is 1mm-150mm, and the thickness is 1mm-20mm; the aluminum woven tape 4 is made of aluminum or aluminum alloy, for example, the length of the aluminum woven tape 4 is 1mm-5000mm, the width is 1mm-150mm, and the thickness is 1mm-20mm, and the diameter of the single wire of the aluminum woven tape 4 is 0.01mm-2mm.

[0083] As shown in Figure 1 , Figure 4 in the third specific embodiment, the copper material is FFC 5, the aluminum material is aluminum bar 6, the preset pressure used in step S200 is 1Mpa-15Mpa, the preset temperature used in step S300 is 460℃-600℃, and the preset time is 1s-1000s.

[0084] In this embodiment, the method of high polymer diffusion welding is used to realize the metal bond connection between the FFC 5 and the aluminum bar 6, and the increase of the resistance at the connection is less than or equal to 0.5mΩ.

[0085] In this embodiment, the copper bar 1 is made of copper or copper alloy, for example, the length of the copper bar 1 is 1mm-5000mm, the width is 1mm-150mm, and the thickness is 1mm-20mm; the aluminum woven tape 4 is made of aluminum or aluminum alloy, for example, the length of the aluminum woven tape 4 is 1mm-5000mm, the width is 1mm-150mm, and the thickness is 1mm-20mm, and the diameter of the single wire of the aluminum woven tape 4 is 0.01mm-2mm, and the single wire is welded at one time.

[0086] The second aspect of the present application provides a copper-aluminum composite substrate connected by the copper-aluminum material connection method according to the first aspect, i.e., the copper material and the aluminum material of the copper-aluminum composite substrate form a metal bond connection.

[0087] The copper-aluminum composite substrate of the present application is welded by the method of high polymer diffusion welding, and a metal bond connection is formed between the copper material and the aluminum material, the conductivity loss at the welding site is small, and the electrochemical corrosion at the welding site is not easy to occur, solving the problems of large brittleness of the welding joint, easy production of pores and cracks in the welding seam, and electrochemical corrosion in the existing copper-aluminum connection structure. The other beneficial effects of the present embodiment are the same as those of the first aspect, and will not be described here.

[0088] In the first embodiment, as shown in Figure 2 , the copper-aluminum composite substrate is a structure connected by the copper-aluminum material connection method according to the first specific embodiment of the first aspect, and the aluminum foil 2 is a structure of one or more layers of stacked welding.

[0089] In the second embodiment, as shown in Figure 3As shown, the copper-aluminum composite substrate is a structure formed by connecting the copper buss 1 and the aluminum braided tape 4 according to the second specific implementation of the copper-aluminum material connecting method in Embodiment One.

[0090] In a third embodiment, as shown, the copper-aluminum composite substrate is a structure formed by connecting the FFC 5 and the aluminum buss 6 according to the third specific implementation of the copper-aluminum material connecting method in Embodiment One. Figure 4

[0091] Embodiments of the third aspect of the present application provide a wire harness including a copper conductor and an aluminum conductor, the copper conductor and the aluminum conductor of the wire harness being connected according to the copper-aluminum material connecting method in Embodiment One, i.e., the copper conductor and the aluminum conductor of the wire harness form a metallic bond connection.

[0092] Unlike existing copper wire harnesses, the wire harness of the present application uses aluminum conductors with a smaller density to replace part of the copper conductors, thereby reducing the mass of the wire harness. In addition, the copper conductors and the aluminum conductors in the wire harness of the present application are welded by a high polymer diffusion welding method, a metallic bond connection is formed between the copper conductors and the aluminum conductors, the conductivity loss at the welding site is small, and electrochemical corrosion is less likely to occur at the welding site. Other beneficial effects of the present embodiment are the same as those of Embodiment One, and will not be described here.

[0093] In some embodiments, the wire harness is a wire harness for an automobile.

[0094] In some embodiments, the wire harness is a wire harness for an automobile.

[0095] Unlike existing copper wire harnesses for automobiles, the wire harness for an automobile of the present application uses aluminum conductors with a smaller density to replace part of the copper conductors, the mass of the wire harness is smaller, thereby reducing the mass of the entire vehicle and achieving weight reduction of the entire vehicle. In addition, since a metallic bond connection is formed between the copper conductors and the aluminum conductors in the wire harness, the conductivity loss at the welding site is small, and electrochemical corrosion is less likely to occur at the welding site, thereby improving the safety and reliability of driving.

[0096] The above description is merely illustrative of the embodiments of the present application and is not intended to limit the scope of the present application. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present application shall fall within the scope of the present application. It should be noted that the components of the present application are not limited to the above overall applications, and the technical features described in the specification of the present application can be selected for individual use or combined for use, therefore, the present application naturally covers other combinations and specific applications related to the inventive points of the present application.​

Claims

1. A method for connecting copper and aluminum materials, used to connect copper and aluminum materials to be connected, characterized in that, The copper-aluminum connection method includes: Step S100: The copper part to be connected and the aluminum part to be connected are stacked together, wherein an intermediate layer is provided between the copper part to be connected and the aluminum part to be connected, and the material of the intermediate layer includes flux and at least one of zinc, silver, nickel, magnesium and silicon. Step S200: Apply pressure simultaneously to the copper part to be connected and the aluminum part to be connected until a preset pressure is reached. During this process, the copper and aluminum parts to be connected are not heated. Under the action of the preset pressure, the micro-protrusions on the contact surfaces of the copper and aluminum parts undergo plastic deformation at the contact points, and the surface oxide film of the parts to be connected is crushed during the deformation. Step S300: Maintain the preset pressure, and simultaneously apply a preset temperature to the copper part to be connected and the aluminum part to be connected and maintain it for a preset time, so as to perform polymer diffusion welding on the copper part to be connected and the aluminum part to be connected, so that a metal bond connection is formed between the contact surfaces of the copper part to be connected and the aluminum part to be connected. The intermediate layer fills the micropores on the surface of the copper and aluminum after being heated and liquefied, and improves the surface energy of the copper and aluminum.

2. The copper-aluminum connection method as described in claim 1, characterized in that, The preset temperature is less than or equal to the solid-phase transformation temperature of the aluminum material, and greater than or equal to the softening temperature of the aluminum material.

3. The copper-aluminum connection method as described in claim 1, characterized in that, The preset temperature is 460℃~600℃, the preset pressure is 1Mpa~15Mpa, and the preset time is 1s~1000s.

4. The copper-aluminum connection method as described in claim 3, characterized in that, The preset temperature is 460℃~550℃, the preset pressure is 3Mpa~11Mpa, and the preset time is 6s~60s.

5. The copper-aluminum connection method as described in claim 1, characterized in that, The copper material is made of copper or a copper alloy, and the aluminum material is made of aluminum or an aluminum alloy.

6. The copper-aluminum connection method as described in claim 1, characterized in that, The copper material may be a copper busbar, copper foil, copper braided mesh, copper wire, or flexible flat cable; The aluminum material is aluminum busbar, aluminum foil, aluminum braided mesh, aluminum wire, or aluminum braided strip.

7. The copper-aluminum connection method as described in claim 1, characterized in that, The intermediate layer also includes at least one of copper and aluminum.

8. The copper-aluminum connection method as described in claim 1, characterized in that, The intermediate layer is a solder sheet, liquid solder, foil, electroplating layer, spray coating layer, or vapor deposition layer.

9. The copper-aluminum connection method according to any one of claims 1 to 5, characterized in that, In step S100, the surface of the aluminum material to be connected is provided with an anti-oxidation protective layer.

10. The copper-aluminum connection method as described in claim 9, characterized in that, The anti-oxidation protective layer is a zinc layer or a copper-zinc alloy layer.

11. The copper-aluminum connection method according to any one of claims 1 to 5, characterized in that, The copper-aluminum connection method also includes the following steps prior to step S100: The surfaces of the copper material and the aluminum material to be connected are cleaned.

12. A copper-aluminum composite substrate, characterized in that, The copper-aluminum composite substrate is formed by connecting copper and aluminum materials to be joined according to any one of claims 1 to 11.

13. A wire harness, characterized in that, The wire harness includes a copper conductor and an aluminum conductor, and the copper conductor and the aluminum conductor are connected according to any one of claims 1 to 11.

14. The wire harness as described in claim 13, characterized in that, The wiring harness is an automotive wiring harness.

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