Full-copper-clad processing method for copper-clad aluminum bar

Abstract

The invention relates to the technical field of copper-aluminum composite material processing, in particular to a full-copper-clad processing method for a copper-clad aluminum busbar, which comprises the following steps of: cutting the end surface of a copper-clad aluminum busbar blank by using a vertical CNC (computerized numerical control) milling machine or punching a blank body to form a to-be-clad copper layer; after the aluminum core area with the end face cut or punched is cleaned, a copper-aluminum binding agent is smeared, and then the aluminum core area stands at the room temperature; a full-coated copper workpiece is formed through two times of extrusion operation; and putting the full-copper-clad workpiece into a box-type resistance furnace for heat treatment, and then cooling to room temperature along with the furnace to form the full-copper-clad copper-clad aluminum busbar for strengthening the copper-aluminum interface bonding force. The full-copper-clad processing method comprises full-copper-clad processing applied to the end face and full-copper-clad processing of the hole, full-copper-clad operation is achieved through the copper layer of the copper-clad aluminum bar, the processing efficiency is effectively improved, and the cost is saved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper-aluminum composite material processing, and particularly relates to a full copper processing method for copper-clad aluminum bars. BACKGROUND

[0002] The copper-clad aluminum material is profiled, and the aluminum core of the end face and the hole is easy to be exposed, which leads to poor corrosion resistance of the material in special environments. In view of the new demand of the market for the traditional copper-aluminum composite bar that the thickness of the copper cladding on the end face and the hole needs to reach more than 0.1% of the thickness of the outer copper material, the existing technology mainly adopts copper plating process, but the process has two defects: (1) Insufficient copper layer thickness: the thickness of the copper plating layer is only 0.005mm-0.01mm, which cannot meet the actual use requirements; (2) Poor cladding integrity: it is difficult to uniformly plate copper on the inner wall of the hole and the end face of the copper-clad aluminum bar, and the areas of missed plating and less plating are easy to occur, which further reduces the corrosion resistance.

[0003] Therefore, a full copper processing method for copper-clad aluminum bars is provided. SUMMARY

[0004] In order to solve the above technical problems, the application provides a full copper processing method for copper-clad aluminum bars, which realizes the copper cladding on the end face and the hole of the copper-clad aluminum bar, and effectively solves the corrosion failure problem of the copper-clad aluminum bar caused by aluminum leakage, and is suitable for harsh environment applications such as power transmission and automobile electronics.

[0005] In order to achieve the above purpose, the technical scheme adopted by the application is: In a first aspect, the application provides a full copper processing method for copper-clad aluminum bars, which is applied to end face copper cladding processing and specifically includes the following specific steps: S1. A vertical CNC milling machine is used to cut the end face of the copper-clad aluminum bar blank while reserving a first epitaxial copper layer and a second epitaxial copper layer on the end face; S2. After cleaning the aluminum core area between the first epitaxial copper layer and the second epitaxial copper layer, a copper-aluminum bonding agent is applied, and then the sample is left at room temperature; S3. A hydraulic press is used to apply a pressure of 12-18MPa to the first epitaxial copper layer and the second epitaxial copper layer in cooperation with a special mold to perform the first end face copper cladding, so that the first epitaxial copper layer and the second epitaxial copper layer are extruded towards the aluminum core to preliminarily cover the aluminum core area, and the copper layer is fully contacted with the applied copper-aluminum bonding agent through the first extrusion; S4. The pressure of the hydraulic press is adjusted to 20-25MPa to perform the second end face copper cladding extrusion operation, which compacts the gap and smooths the edge to ensure that there is no exposed area of the aluminum core, and a full copper workpiece is formed through the second extrusion; S5. Put the full copper package copper-aluminum workpiece into the box resistance furnace for heat treatment, and then cool it to room temperature in the furnace to form a full copper package copper-aluminum row with strengthened copper-aluminum interface bonding force. Wherein, the first and second epitaxial copper layers have the same extension length, and the end faces of the first and second epitaxial copper layers coincide after extrusion and completely cover the surface of the aluminum core.

[0006] Further, the spindle speed of the vertical CNC milling machine is 2500 r / min, and the feed speed is 400 mm / min.

[0007] Further, the copper-aluminum bonding agent comprises a main binder of 60%-70% modified epoxy resin and a filler of 25%-35% copper powder, and the particle size of the copper powder is 5-10 Wherein, the thickness of the copper-aluminum bonding agent applied on the aluminum core area is 0.05-0.2 mm.

[0008] Further, when the full copper package copper-aluminum workpiece is put into the box resistance furnace for heat treatment, the heating rate of the box resistance furnace is set to 5 ℃ / min, and the temperature is raised to 250-450 ℃, and then the full copper package copper-aluminum workpiece is kept in the box resistance furnace for 60-100 min.

[0009] In the second aspect, the application provides a full copper processing method for a copper-aluminum row, which is applied to hole copper processing and specifically includes the following steps: S1. A vertical CNC milling machine is used to mill the predetermined position of the copper-aluminum row blank to perform a punching operation, and the copper layer to be coated on both sides of the hole is reserved; S2. After the aluminum chips in the hole area are cleaned, the copper-aluminum bonding agent is applied to the aluminum core area of the hole wall, and then it is left at room temperature; S3. A hydraulic pressing machine is used to apply a pressure of 15-20 MPa to the copper layer of the hole from the outside to the inside by cooperating with a special mold to perform the first copper coating extrusion, so as to extrude the copper layer to be coated from the outside to the aluminum core of the hole wall to preliminarily cover the aluminum core area of the hole wall, and the copper layer to be coated is fully contacted with the applied copper-aluminum bonding agent through the first extrusion; S4. The pressure of the hydraulic pressing machine is adjusted to 22-28 MPa to perform the second copper coating extrusion, so as to compact the gap and smooth the edge, ensure that there is no exposed area of the aluminum core, and form a full copper package copper-aluminum workpiece through the second extrusion; S5. Put the full copper package copper-aluminum workpiece into the box resistance furnace for heat treatment, and then cool it to room temperature in the furnace to form a full copper package copper-aluminum row with strengthened copper-aluminum interface bonding force. Wherein, the copper layer to be coated completely covers the surface of the aluminum core of the hole wall after extrusion.

[0010] Further, the copper-aluminum bonding agent comprises a main binder of 60%-70% modified epoxy resin and a filler of 25%-35% copper powder, the particle size of the copper powder is 5-10 The thickness of the copper-aluminum bonding agent applied in the aluminum core area is 0.05mm-0.2mm.

[0011] Further, when the full-copper-coated workpiece is placed in the box-type resistance furnace for heat treatment, the heating rate of the box-type resistance furnace is set to 5℃ / min, and after the temperature is raised to 250℃-450℃, the full-copper-coated workpiece is kept in the box-type resistance furnace for 60-100min.

[0012] The beneficial effects of the present application are: (1) The copper layer thickness and the coating integrity of the copper-coated aluminum bar after processing are more superior to the existing copper-coated aluminum bar, and fully meet the precision requirements. (2) After the copper layer is reserved and twice extruded, the copper layer thickness is stable to 0.1%-0.3% of the thickness of the outer copper material, and there is no any plating leakage area. The experiment shows that the copper layer thickness is 2-24 times of that of the traditional process.

[0013] (3) The copper-aluminum interface bonding force of the copper-coated aluminum bar after processing is stronger, and the working condition adaptability is better.

[0014] (4) The present application cooperates with the bonding agent and heat treatment, and the bonding force reaches 25-60MPa, which is 5.8 times of that of the traditional process. The tensile shear experiment verifies that the coated part is not layered after 1000 times of vibration test (20Hz, 1mm amplitude).

[0015] (5) The corrosion resistance of the copper-coated aluminum bar after processing is similar to that of pure copper, and it is suitable for harsh environments. (6) After eliminating aluminum leakage, the present application is processed according to the pure copper plating layer process, and there is no corrosion and discoloration in 48h salt spray test, and the corrosion resistance is consistent with that of pure copper, which is 8 times higher than that of the traditional process, and can be directly used in humid / salt spray environment such as power transmission and automobile electronics.

[0016] (7) The processing cost of the present application is lower, the efficiency is higher, and the yield is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The present application provides a full-copper-coated copper-coated aluminum bar processing method.

[0018] Figure 2 The present application provides a full-copper-coated copper-coated aluminum bar processing method.

[0019] Figure 3This is a schematic diagram of the process applied to the hole-cladding copper processing method in the full copper cladding method of the copper-clad aluminum busbar proposed in this invention.

[0020] Figure 4 This is a schematic diagram of the hole processing dimensions used in the hole-cladding copper process of a copper-clad aluminum busbar processing method proposed in this invention.

[0021] Figure 5 This is a schematic diagram of the process flow of the copper-clad aluminum busbar applied in the hole-cladding copper processing of a copper-clad aluminum busbar according to the present invention. Detailed Implementation

[0022] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0023] Example 1. like Figures 1-2 As shown, this embodiment provides a method for fully encasing copper in a copper-clad aluminum busbar, applied to end-coating copper processing. A 50mm×50mm×6mm copper-clad aluminum busbar blank is selected, wherein the aluminum base has a purity of 99.7%, and the outer copper layer is 0.8mm thick, with the copper layer uniformly covering the outer surface of the aluminum base. A copper-aluminum binder is used. The entire process utilizes the copper material of the copper-clad aluminum busbar itself for extrusion cladding, specifically including the following steps: S1. A vertical CNC milling machine is used to cut the end face of the copper-clad aluminum billet while reserving the first and second extended copper layers on the end face.

[0024] In this embodiment, the spindle speed of the vertical CNC milling machine (Computer Numerical Control Machining) is 2500 r / min, and the feed rate is 400 mm / min. Figure 2 As shown, the end face shape tolerance of the copper-clad aluminum busbar blank in this embodiment is ±0.03mm-±0.05mm, and the chamfer angle between the copper layer formed after cutting and the axis of the copper busbar is 45 degrees. Figure 3As shown, after the end face of the copper-clad aluminum bar blank is cut by the vertical CNC milling machine, the extended copper layer of the end face is formed, and the two end faces of the copper-clad aluminum bar blank respectively include the first epitaxial copper layer on the upper side and the second epitaxial copper layer on the lower side. It should be noted that the first epitaxial copper layer and the second epitaxial copper layer have the same extension length, and after extrusion, the end faces of the first epitaxial copper layer and the second epitaxial copper layer coincide and completely cover the surface of the aluminum core. Therefore, in actual cutting, the size of the copper-clad aluminum blank needs to be calculated, and the cutting is performed according to the calculated length of the epitaxial copper layer, so as to ensure that the epitaxial copper layers on both sides completely cover the surface of the aluminum core after extrusion. The specific calculation process of the size belongs to the conventional calculation content and can be realized by measurement. The present embodiment does not make specific limitation on this part.

[0025] S2. After the aluminum core region between the first epitaxial copper layer and the second epitaxial copper layer is cleaned, a copper-aluminum bonding agent is applied, and then the room temperature is kept.

[0026] In the present embodiment, in order to realize that the first epitaxial copper layer and the second epitaxial copper layer completely cover the aluminum core after extrusion, a copper-aluminum bonding agent is prepared in the present embodiment. The copper-aluminum bonding agent includes a main binder of 60%-70% modified epoxy resin and a filler of 25%-35% copper powder. The particle size of the copper powder is 5-10 In the present embodiment, a pneumatic dispensing machine (model AD-982) is used to apply the bonding agent only to the exposed aluminum core region. After the application is completed, the room temperature (25°C) is kept for 8 minutes to ensure that there is no air bubble.

[0027] S3. A hydraulic pressing machine is used to apply a pressure of 15 MPa to the first epitaxial copper layer and the second epitaxial copper layer in cooperation with a special mold to perform the first end face copper cladding, so that the first epitaxial copper layer and the second epitaxial copper layer are extruded towards the aluminum core to preliminarily cover the aluminum core region, and the copper layer is in full contact with the applied copper-aluminum bonding agent through the first extrusion.

[0028] In the present embodiment, the model of the hydraulic pressing machine is YQ32-100. The special mold is used to apply a pressure of 15 MPa to the first epitaxial copper layer and the second epitaxial copper layer to perform the first end face copper cladding, so that the first epitaxial copper layer and the second epitaxial copper layer are extruded towards the aluminum core to preliminarily cover the aluminum core region, and the extrusion time is kept for about 15 seconds. The copper layer is in full contact with the applied copper-aluminum bonding agent through the first extrusion. It should be noted that the special mold of the present embodiment is an existing mold specially used for extrusion of copper-clad aluminum bars, which is mainly used for extruding the first epitaxial copper layer and the second epitaxial copper layer. The present embodiment does not make specific limitation on the special mold.

[0029] S4. Adjust the pressure of the hydraulic press to 22 MPa, and perform a second end face copper cladding extrusion operation to compact the gap and smooth the edges, and ensure that the aluminum core has no exposed areas, and form a full copper cladding workpiece through the second extrusion.

[0030] In this embodiment, when the pressure of the hydraulic press is adjusted to 22 MPa to perform a second end face copper cladding extrusion operation, a higher precision shaping die (such as a cavity precision of ±0.005 mm) is used, and after the second extrusion, the gap is compacted and the edges are smoothed, and the extrusion time is maintained at about 20 s, and the aluminum core is ensured to have no exposed areas, and a full copper cladding workpiece is formed through the second extrusion.

[0031] S5. Put the full copper cladding workpiece into a box-type resistance furnace for heat treatment, and then cool it to room temperature in the furnace, to form a full copper cladding copper-clad aluminum bar with strengthened copper-aluminum interface bonding force.

[0032] In this embodiment, when the full copper cladding workpiece is put into the box-type resistance furnace for heat treatment, the heating rate of the box-type resistance furnace is set to 5°C / min, and after heating to 380°C, the full copper cladding workpiece is kept in the box-type resistance furnace for 80 min. After cooling to room temperature in the furnace, a full copper cladding copper-clad aluminum bar with strengthened copper-aluminum interface bonding force is formed, and the copper-aluminum interface bonding force is detected to be 52 MP.

[0033] Embodiment 2. As shown in Figures 3-5 , the present embodiment provides a full copper cladding processing method for a copper-clad aluminum bar, which is applied to hole copper cladding processing, and a copper-clad aluminum bar blank with a size of 50 mm×50 mm×6 mm is selected, wherein the purity of the aluminum base is 99.7%, the thickness of the outer copper layer is 0.8 mm, and the copper layer is uniformly coated on the outer surface of the aluminum base; a copper-aluminum bonding agent is matched; the reserved copper material in the hole layer of the copper-clad aluminum bar itself is used for extrusion cladding throughout the process, which specifically includes the following specific steps: S1. A vertical CNC milling machine is used to mill the predetermined position of the copper-clad aluminum bar blank to perform a punching operation, and the copper layer on both sides of the hole to be cladded is reserved.

[0034] In this embodiment, as shown in Figure 4 , the copper-clad aluminum bar blank is processed into the actual required shape of the hole, and the milling process reserves copper layers on the upper and lower hole sides, the reserved copper layers are used as the copper layers to be cladded, and the thickness of the reserved upper and lower copper layers is 0.8 mm, the middle milled part is an aluminum core, the diameters of the upper side, the lower side and the middle part of the hole are the depths of the reserved corresponding metal layers, so as to facilitate copper cladding, as shown in Figure 4 , the upper hole diameter is left as 3.8 mm; the middle milling diameter is 9.2 mm; and the lower hole is a diameter of 6.2 mm, and the shape tolerance is controlled within ±0.03 mm-±0.05 mm.

[0035] S2. After the de-alumination cleaning treatment of the region in the hole, the copper-aluminum bonding agent is applied to the aluminum core region of the inner wall of the hole, and then it is left at room temperature.

[0036] In this embodiment, in order to realize that the copper layer to be coated is completely covered with the aluminum core after extrusion, the copper-aluminum bonding agent is prepared, which includes a main binder of modified epoxy resin accounting for 60%-70% and a filler of copper powder accounting for 25%-35%, and the particle size of the copper powder is 5-10 In this embodiment, the pneumatic dispensing machine (model AD-982) is used to uniformly apply the bonding agent to the exposed aluminum core region of the inner wall of the hole, and the thickness is controlled to be 0.05-0.2 mm. After the application is completed, it is left at room temperature (25°C) for 8 min to ensure that there is no bubble and no accumulation.

[0037] S3. The hydraulic press is used to apply a pressure of 18 MPa to the copper layer to be coated from the outside to the inside, and the first copper coating extrusion is performed to extrude the copper layer to be coated from the outside to the aluminum core of the inner wall, and the extrusion time is maintained for about 18 s to preliminarily cover the aluminum core region of the inner wall, so that the copper layer is in full contact with the applied copper-aluminum bonding agent.

[0038] S4. The pressure of the hydraulic press is adjusted to 22-28 MPa to perform the second copper coating extrusion to compact the gap and smooth the edge, and the extrusion time is maintained for about 25 s to ensure that there is no exposed region of the aluminum core, and the full copper workpiece is formed through the second extrusion.

[0039] In this embodiment, the upper hole side and the lower hole side each reserve 2.7 mm and 1.5 mm of the reserved copper layer to form a copper layer to be coated with a length of 4.2 mm and a thickness of 0.8 mm. After extrusion, the copper layer to be coated is extruded into a copper coating layer with a thickness of 0.1 mm and a length of 6 mm, and after the extrusion is completed, the full copper workpiece with the copper coating layer is formed.

[0040] S5. The full copper workpiece is placed in a box-type resistance furnace for heat treatment, and then cooled to room temperature in the furnace to form a full copper copper-clad aluminum row with strengthened copper-aluminum interface bonding force.

[0041] In this embodiment, when the full copper workpiece is placed in the box-type resistance furnace for heat treatment, the heating rate of the box-type resistance furnace is set to 5°C / min, and the full copper workpiece is heated to 380°C and then kept in the box-type resistance furnace for 80 min. After cooling to room temperature in the furnace, a full copper copper-clad aluminum row with strengthened copper-aluminum interface bonding force is formed.

[0042] Comparative example: The comparative example in this embodiment uses the same copper-clad aluminum busbar blank as in Examples 1 and 2, and performs copper plating on the end face and holes. The comparative example uses a traditional copper plating process, which involves pre-treating the copper-clad aluminum busbar blank with the end face cut or the copper-clad aluminum busbar blank that has undergone processing by degreasing (alkaline degreasing agent, soaking at 65°C for 15 min) → pickling (12% hydrochloric acid, soaking at room temperature for 8 min) → activation (6% sulfuric acid, soaking at room temperature for 3 min) → water washing, and then drying at 100°C for 5 min to form the copper-clad aluminum busbar to be copper plated. Copper plating: Copper plating is performed on the copper-clad aluminum busbar using a rack plating method, where the copper-clad aluminum busbar acts as the cathode and pure copper as the anode; the plating bath temperature is 30℃, and the current density is 1.2A / dm³. 2 Electroplating time: 40 minutes.

[0043] Post-treatment: water washing → chromate passivation (immersion at room temperature for 5 minutes) → drying at 90℃ for 15 minutes to form copper-clad aluminum busbars after copper plating.

[0044] After comparing the processing results of Examples 1 / 2 and the comparative examples, the test results are shown in Table 1. The copper-clad scheme refers to the copper-clad technology schemes of Examples 1 and 2, and the copper plating scheme refers to the content of the comparative example. See Table 1 for details. Table 1: Comparison of Test Results

[0045] Through the above comparative analysis, Examples 1 and 2 achieve complete copper-clad aluminum busbar coverage by using their own copper layer and then extruding it twice. The copper plating process in the comparative example suffers from severe plating omissions in large-sized workpieces due to uneven coverage of the plating solution. Secondly, the copper layer thickness in Examples 1 and 2 ensures full coverage, while the copper layer in the comparative example is thinner and has local gaps, failing to meet the requirements for conductivity and protection. The bonding strength of the copper-clad aluminum busbars obtained in Examples 1 and 2 is 52 MPa, which can withstand 1000 vibration tests, while the bonding strength in the comparative example is 9 MPa, which cracks after 50 vibrations. In addition, the full copper-clad solution used in Examples 1 and 2 does not require additional copper material, and the processing time of a single copper-clad aluminum busbar is 50% shorter than that in the comparative example, with a yield rate of 98%. In contrast, the copper plating process in the comparative example requires multiple re-plating processes, increasing costs by 40% and achieving only a 40% yield rate.

[0046] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for fully encasing aluminum busbars in copper, characterized in that, This method is applied to the copper plating process at the ends and includes the following specific steps: S1. While cutting the end face of the copper-clad aluminum busbar blank using a vertical CNC milling machine, a first and a second epitaxial copper layer are reserved on the end face. S2. After cleaning the aluminum core area between the first and second epitaxial copper layers, apply copper-aluminum bonding agent and let it stand at room temperature. S3. Using a hydraulic press and a special mold, apply 12-18MPa pressure to the first and second epitaxial copper layers to perform the first end-copper coating, so that the first and second epitaxial copper layers are squeezed toward the aluminum core to initially cover the aluminum core area. The first extrusion allows the copper layers to fully contact the applied copper-aluminum binder. S4. Adjust the pressure of the hydraulic press to 20-25MPa, perform the second end-copper extrusion operation, compact the gap, smooth the edges, and ensure that there are no exposed areas of the aluminum core. The second extrusion forms a fully encased copper workpiece. S5. The fully encased copper workpiece is placed in a box-type resistance furnace for heat treatment, and then cooled to room temperature with the furnace to form a fully encased copper-clad aluminum busbar with enhanced copper-aluminum interfacial bonding. The first and second epitaxial copper layers have the same extension length. After extrusion, the end faces of the first and second epitaxial copper layers overlap and completely cover the surface of the aluminum core.

2. The method for fully encasing copper in a copper-clad aluminum busbar according to claim 1, characterized in that, The vertical CNC milling machine has a spindle speed of 2500 r / min and a feed rate of 400 mm / min.

3. The method for fully encasing copper in a copper-clad aluminum busbar according to claim 1, characterized in that, The copper-aluminum binder comprises a main binder of 60%-70% modified epoxy resin and a filler of 25%-35% copper powder, the copper powder having a particle size of 5-10 mm. The thickness of the copper-aluminum binder applied to the aluminum core area is 0.05mm-0.2mm.

4. A method for fully encasing copper in a copper-clad aluminum busbar according to claim 1, characterized in that, When placing the fully encased copper workpiece into a box-type resistance furnace for heat treatment, the heating rate of the box-type resistance furnace is set to 5℃ / min, and after heating to 250℃-450℃, the fully encased copper workpiece is held in the box-type resistance furnace for 60-100min.

5. A method for fully encasing aluminum busbars in copper, characterized in that, This method is applied to the copper cladding process and includes the following specific steps: S1. A drilling operation is performed by using a vertical CNC milling machine to mill the copper-clad aluminum billet at a predetermined position, retaining the copper layer to be clad on both sides of the hole; S2. After cleaning the area inside the hole to remove aluminum shavings, apply copper-aluminum bonding agent to the aluminum core area on the inner wall of the hole, and then let it stand at room temperature. S3. Using a hydraulic press and a special mold, apply 15-20MPa pressure to the copper layer of the hole from the outside to the inside to perform the first copper coating extrusion. The copper layer to be coated is extruded from the outside to the aluminum core of the hole to initially cover the aluminum core area of ​​the hole. The first extrusion ensures that the copper layer to be coated is in full contact with the applied copper-aluminum binder. S4. Adjust the pressure of the hydraulic press to 22-28MPa, perform a second copper cladding extrusion, compact the gaps, smooth the edges, and ensure that there are no exposed areas of the aluminum core. The second extrusion forms a fully clad copper workpiece. S5. The fully encased copper workpiece is placed in a box-type resistance furnace for heat treatment, and then cooled to room temperature with the furnace to form a fully encased copper-clad aluminum busbar with enhanced copper-aluminum interfacial bonding. The copper layer to be coated completely covers the surface of the aluminum core inside the hole after being extruded.

6. A method for fully encasing copper in a copper-clad aluminum busbar according to claim 5, characterized in that, The copper-aluminum binder comprises a main binder of 60%-70% modified epoxy resin and a filler of 25%-35% copper powder, the copper powder having a particle size of 5-10 mm. The thickness of the copper-aluminum binder applied to the aluminum core area is 0.05mm-0.2mm.

7. A method for fully encasing copper in a copper-clad aluminum busbar according to claim 5, characterized in that, When placing the fully encased copper workpiece into a box-type resistance furnace for heat treatment, the heating rate of the box-type resistance furnace is set to 5℃ / min, and after heating to 250℃-450℃, the fully encased copper workpiece is held in the box-type resistance furnace for 60-100min.

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