Ultra-thin aluminum-copper composite strip with ultra-thin interface and preparation method thereof

Abstract

An ultra-thin aluminum-copper composite strip with an ultra-thin interface and a preparation method thereof, the strip is formed by rolling and compounding aluminum foil and copper foil; wherein the composition of the aluminum foil is: 0.2%-0.4% magnesium, 0.01%-0.03% erbium, and the remainder is aluminum or aluminum alloy; the composition of the copper foil is electronic oxygen-free copper with a purity of ≥99.99%; the thickness of the composite strip combined interface layer is ≤0.01mm, the copper-aluminum thickness ratio is 1 / 9-1 / 11, and the thickness of the strip is 0.18-0.24mm. The preparation method comprises: leveling and polishing the surfaces of the aluminum alloy and the copper, obtaining a preformed ingot by stir friction welding, and obtaining it by cold rolling composite forming, intermediate rolling forming, precision rolling forming, and finished product annealing. This method can control the thickness of the composite layer, realize the effective compounding of the ultra-thin aluminum-copper composite strip, and at the same time obtain an infinitely long surface with good forming quality, realize the mass production of ultra-thin aluminum-copper composite strips with ultra-thin interfaces, and realize the application in electronic products.

Description

Technical Field

[0001] The invention belongs to the technical field of metal composite strip preparation, and in particular relates to an ultra-thin aluminum-copper composite strip with an ultra-thin interface and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, modern technology has some contradictory requirements for the application of materials in addition to conventional physical, chemical and mechanical properties, such as good electrical conductivity, high thermal conductivity, low contact resistance and bright outer surface, but the price must be low. It is difficult for a single metal material to meet these requirements at the same time, so composite materials came into being, which have excellent comprehensive properties and lower prices.

[0003] Aluminum-copper composite material is a new type of composite material. It has the advantages of copper's good electrical conductivity, high thermal conductivity, and low contact resistance, as well as aluminum's low price. Aluminum-copper composite materials also have the advantages of light weight and corrosion resistance. They not only maintain the excellent properties of the original metal, but also have better comprehensive performance than single metals. They can be used in various fields such as rail transportation, power electronics, aerospace, petrochemicals, and daily necessities.

[0004] There are many methods for preparing aluminum-copper composite materials, such as explosive composite, solid-liquid composite, brazing composite, diffusion welding composite, rolling composite, stir friction welding composite, etc. At present, aluminum-copper composite materials prepared by various composite technologies have a solid solution zone formed by atomic diffusion at the composite interface, which improves the interface bonding strength, but it is very easy to form brittle and hard intermetallic compounds at the composite interface, which not only reduces the mechanical properties of the material, but also leads to a thicker composite layer, affecting the comprehensive performance of the material. It is also difficult to achieve the connection of aluminum-copper composite materials and realize large-scale production.

[0005] Therefore, how to reduce the formation of the intermediate phase, ensure the thickness of the composite layer, and achieve the connection of aluminum-copper composite materials is the key to achieving high-quality mass production of aluminum-copper composite strips. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides an ultra-thin aluminum-copper composite strip with an ultra-thin interface and a preparation method thereof, which can achieve effective composite of ultra-thin aluminum-copper composite strips, effectively reduce the thickness of the composite interface, and realize the connection of aluminum-copper composite materials.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The invention discloses an ultra-thin aluminum-copper composite strip with an ultra-thin interface, which is formed by rolling and compounding aluminum foil and copper foil; wherein the aluminum foil comprises 0.2%-0.4% magnesium, 0.01%-0.03% erbium, and the remainder is aluminum or aluminum alloy; the copper foil comprises electronic oxygen-free copper with a purity of ≥99.99%; the thickness of the composite strip bonding interface layer is ≤0.01mm, the copper-aluminum thickness ratio is 1 / 9-1 / 11, and the thickness of the strip is 0.18-0.24mm.

[0009] As described above, the ultra-thin aluminum-copper composite strip with an ultra-thin interface, preferably, the aluminum alloy is one of 2 series, 3 series, 4 series, 5 series, 6 series and 7 series aluminum alloys.

[0010] On the other hand, the present invention provides a method for preparing an ultra-thin aluminum-copper composite strip with an ultra-thin interface, the method comprising the following steps:

[0011] I. Smelting and casting aluminum alloy ingots and pure copper ingots, and rolling the aluminum ingots and copper ingots into thin plates; wherein the composition of the aluminum alloy ingot is: 0.2%-0.4% magnesium, 0.01%-0.03% erbium, and the balance is aluminum or aluminum alloy; the composition of the copper ingot is electronic oxygen-free copper with a purity of ≥99.99%;

[0012] II. Take aluminum-copper plates of the same width and length, level them first and then polish the surface; then clean the surface, stack the aluminum-copper plates, and stir-friction weld one end for preforming;

[0013] III. Rolling and cladding the preformed aluminum-copper material;

[0014] IV. The aluminum-copper composite sheet is connected end to end by friction stir welding to form a long sheet;

[0015] V. Performing intermediate rolling forming on the connected aluminum-copper composite long plate to complete further strip forming;

[0016] VI. Finish rolling and coiling the aluminum-copper composite strip;

[0017] VII. The aluminum-copper composite material after fine rolling and coiling is subjected to finished product annealing to obtain an ultra-thin aluminum-copper composite strip with an ultra-thin interface.

[0018] In the preparation method as described above, preferably, in step I, the aluminum ingot is slab-rolled into a thin plate with a thickness of 6.2 to 6.8 mm, and the copper ingot is slab-rolled into a thin plate with a thickness of 0.12 to 0.18 mm.

[0019] In the preparation method as described above, preferably, the surface grinding in step II is carried out by a brush machine, pneumatic sandblasting or an angle grinder equipped with a turbine, and the surface roughness reaches Ra≥3.2; the aluminum plate is placed on top and the copper foil is placed on the bottom for friction stir welding, the stirring head is pressed down to a thickness less than 0.05 to 0.1 mm of the composite plate, the stirring head is tilted at an angle of 1 to 2°, the stirring head speed is 800 to 1500 r / min, the welding speed is 20 to 40 mm / min, and friction stir welding is performed.

[0020] In the preparation method as described above, preferably, the first rolling reduction rate of the composite rolling in step III is not less than 50%, the rolling speed is not greater than 10 cm / s, and the total rolling reduction rate after rolling is 60-80%.

[0021] As described above, preferably, in the friction stir welding of step VI, the copper side is on top and the aluminum side is on the bottom, the stirring head is pressed down to a thickness less than 0.02 to 0.05 mm of the composite plate, the stirring head has an inclination angle of 1 to 2°, the stirring head speed is 800 to 1500 r / min, and the welding speed is 20 to 40 mm / min to perform friction stir welding connection.

[0022] In the preparation method as described above, preferably, the reduction rate of the intermediate rolling forming pass in step V is not less than 40%, and the rolling speed is not more than 50 cm / s.

[0023] In the preparation method as described above, preferably, the reduction rate of the finishing rolling forming pass in step VI is not greater than 20%, and front and rear tension devices are added to reciprocately roll the composite plate after intermediate rolling to reach a finished product thickness of 0.18 to 0.24 mm before coiling.

[0024] In the preparation method as described above, preferably, the finished product annealing in step VI is vacuum annealing at 400-450° C. for 1-2 hours.

[0025] The preparation process of the aluminum alloy melt comprises the following steps:

[0026] Put pure aluminum into a non-vacuum melting furnace and heat it to melt. Adjust the melt temperature to 630-700℃, add pure Mg, keep it warm and stir for 30-60min, then add rare earth elements and keep it warm again for 20-40min. Cast the aluminum alloy melt into a graphite mold, cool and solidify to obtain an aluminum alloy ingot.

[0027] The present invention solves the technical problem that when preparing aluminum-copper foil composite strips, a large amount of intermetallic compounds are formed at the aluminum-copper composite interface, resulting in a thick interface layer, thereby increasing the thickness of the strip and reducing the mechanical properties of the material. To solve this technical problem, the present invention adopts the following technical measures:

[0028] 1. The aluminum alloy side of the composite strip of the present invention adopts the Al-Mg (RE) aluminum alloy system. A small amount of magnesium added to aluminum can enhance the hardness and tensile strength of the aluminum alloy; a trace amount of rare earth element erbium is added to the aluminum alloy to achieve the purpose of grain refinement, increased strength, and improved conductivity. As a result, the aluminum alloy sheet matches the copper sheet in terms of hardness, strength, and conductivity, and the rolling performance and use performance of the composite strip are improved.

[0029] 2. In the preforming step, friction stir welding is used to weld one end of the two metal sheets together, which facilitates the precise control of the feeding operation during rolling.

[0030] 3. The method of the present invention rolls and composites the preformed aluminum-copper composite plate, then connects the composited plates by stir friction welding, and then coils them into strips after intermediate rolling and finish rolling, and finally anneals the finished product. There is only one annealing treatment for multiple rolling operations, which avoids the formation of a large amount of intermetallic compounds in multiple annealing passes. Therefore, the obtained aluminum-copper composite strip has less intermetallic compounds and the composite interface thickness does not exceed 0.01 mm.

[0031] 4. Friction stir welding is used for butt welding between aluminum-copper composite sheets to obtain strips of unlimited length.

[0032] The beneficial effects of the present invention are as follows: the method of the present invention can control the thickness of the composite layer, realize the effective composite of the ultra-thin aluminum-copper composite strip, the thickness of the obtained copper foil layer reaches 0.02 mm, the copper-aluminum thickness ratio reaches 1 / 11, and the thickness of the aluminum-copper composite interface layer is less than or equal to 0.01 mm. At the same time, a surface with infinite length and good forming quality can be obtained. The preparation method is simple, saves the amount of copper, reduces costs, is conducive to mass production, and realizes engineering applications in electronic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an electron microscope photograph of the cross section of the aluminum-copper composite strip of Example 1 of the present invention.

[0034] Figure 2 This is an electron microscope photo of the cross section of the aluminum-copper composite strip of Example 2 of the present invention

[0035] Figure 3 This is an electron microscope photo of the cross section of the aluminum-copper composite strip of Example 3 of the present invention.

[0036] Figure 4 This is an electron microscope photo of the cross section of the aluminum-copper composite strip of comparative example 1 of the present invention.

[0037] Figure 5 It is an operation flow chart of the present invention. DETAILED DESCRIPTION

[0038] The following is a detailed description of an implementation example of the present invention. This example is implemented based on the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following implementation example.

[0039] Example 1

[0040] The operation process of preparing ultra-thin aluminum-copper composite strip with ultra-thin interface is as follows Figure 5 shown.

[0041] Step 1: Material Preparation

[0042] Put pure aluminum into a non-vacuum melting furnace and heat it to melt. Adjust the melt temperature to 630°C, add 0.2wt% pure Mg, keep warm and stir for 40 minutes, then add 0.01wt% erbium, and keep warm again for 30 minutes. Cast the aluminum alloy melt into a graphite mold, cool and solidify to obtain an aluminum alloy ingot.

[0043] Pure copper is refined and cast using a mold of the same size.

[0044] The cast aluminum alloy and copper ingots were respectively subjected to billet rolling, and after intermediate rolling and finish rolling, the aluminum alloy plate thickness δ1 = 6.5 mm ± 0.3 mm and the copper plate δ2 = 0.15 mm ± 0.03 mm were obtained. They were uniformly cut into plates with a width of 250 mm and a length of 1000 mm.

[0045] Put the prepared plate into the leveling machine for plate leveling, put it into the brushing machine and use 100 mesh sandpaper for surface grinding, and the grinding direction of aluminum alloy and copper plates is consistent to achieve surface roughness Ra ≥ 3.2. Remove the surface oxide film, then use the washing liquid to remove surface impurities and oil, rinse the surface with clean water, dehydrate with alcohol, and dry with a hot air machine.

[0046] Step 2: Friction stir welding preform

[0047] The prepared aluminum-copper sheet is fixed to the friction stir welding platform. The welding direction is the width direction of the sheet. A welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid keyholes after welding. The aluminum sheet is on top and the copper sheet is on the bottom. The stirring head is pressed down to penetrate the copper sheet by 0.1mm. The stirring head is tilted at 2°, the stirring head speed is 1500r / min, and the welding speed is 40mm / min. Stir friction welding is performed to complete the preforming of the aluminum-copper dissimilar metal composite sheet.

[0048] Step 3: Rolling the composite

[0049] The preformed aluminum-copper dissimilar metal composite sheet is placed in a rolling mill and rolled at a first pass reduction rate of 80% and a rolling speed of 3 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 3 mm.

[0050] Step 4: Friction stir welding connection

[0051] Two aluminum-copper composite plates that have completed rolling and cladding are connected end to end and fixed to the friction stir welding platform. The welding direction is the width direction of the plate, and a welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid keyholes after welding. The copper side of the composite plate is on the top and the aluminum side is on the bottom. The stirring head is pressed down to less than 0.05mm of the composite plate thickness, the stirring head is tilted at an angle of 2., the stirring head speed is 1500r / min, and the welding speed is 40mm / min, and the friction stir welding connection is performed.

[0052] Step 5: Intermediate rolling

[0053] The aluminum-copper dissimilar metal composite sheet connected by friction stir welding is put into a rolling mill and rolled at a pass reduction rate of 60% and a rolling speed of 20 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 1 mm.

[0054] Step 6: Finishing and Coiling

[0055] The reduction per pass is strictly controlled at 10%. The composite plate after intermediate rolling is reciprocated through the front and rear tension devices and is coiled when the thickness reaches the finished product thickness.

[0056] Step 7: Annealing of finished product

[0057] The rolled aluminum-copper composite material is subjected to a finished product vacuum annealing treatment at 450°C for 1 hour to eliminate the work hardening of the aluminum-copper composite material, thereby obtaining an ultra-thin aluminum-copper composite strip with an ultra-thin interface.

[0058] Figure 1 The cross-section electron microscope photo of the aluminum-copper composite strip obtained. The photo shows that it is mainly composed of aluminum alloy matrix and copper matrix, with a very thin aluminum-copper composite interface in the middle. The thickness of the composite interface copper foil layer is 0.02mm, the thickness of the aluminum alloy thin layer is 0.22mm, the copper-aluminum thickness ratio is 1 / 11, and the thickness of the aluminum-copper composite interface layer is less than 0.01mm. The resistivity of the composite strip was tested, and the results showed that the conductivity of the composite material measured from the aluminum alloy side was 61.3% IACS.

[0059] Example 2

[0060] Step 1: Material Preparation

[0061] The same method as in Example 1 was used to prepare aluminum alloy ingots and copper ingots.

[0062] The cast aluminum alloy and copper ingots were respectively subjected to billet rolling, and after intermediate rolling and finish rolling, the aluminum alloy plate thickness δ1 = 6.5 mm ± 0.3 mm and the copper plate δ2 = 0.15 mm ± 0.03 mm were obtained. They were uniformly cut into plates with a width of 300 mm and a length of 1500 mm.

[0063] Put the prepared plate into the leveling machine for plate leveling, put it into the pneumatic sandblasting machine and select 100 mesh gravel for surface impact to achieve surface roughness Ra ≥ 3.2. Remove the surface oxide film, then use the washing liquid to remove surface impurities and oil, rinse the surface with clean water, dehydrate with alcohol, and dry with a hot air machine.

[0064] Step 2: Friction stir welding preform

[0065] The prepared aluminum-copper sheet is fixed to the friction stir welding platform. The welding direction is the width direction of the sheet. A welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid keyholes after welding. The aluminum sheet is on top and the copper sheet is on the bottom. The stirring head is pressed down to penetrate the copper sheet by 0.1mm. The stirring head is tilted at 2°, the stirring head speed is 1000r / min, and the welding speed is 30mm / min. Stir friction welding is performed to complete the preforming of the aluminum-copper dissimilar metal composite sheet.

[0066] Step 3: Rolling the composite

[0067] The preformed aluminum-copper dissimilar metal composite sheet is placed in a rolling mill and rolled at a first pass reduction rate of 60% and a rolling speed of 8 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 3 mm.

[0068] Step 4: Friction stir welding connection

[0069] Two aluminum-copper composite plates that have completed rolling and cladding are connected end to end and fixed to the friction stir welding platform. The welding direction is the width direction of the plate, and a welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid keyholes after welding. The copper side of the composite plate is on the top and the aluminum side is on the bottom. The stirring head is pressed down to less than 0.05mm of the composite plate thickness, the stirring head is tilted at an angle of 2., the stirring head speed is 1000r / min, and the welding speed is 30mm / min, and the friction stir welding connection is performed.

[0070] Step 5: Intermediate rolling

[0071] The aluminum-copper dissimilar metal composite sheet connected by friction stir welding is put into a rolling mill and rolled at a pass reduction rate of 50% and a rolling speed of 30 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 1 mm.

[0072] Step 6: Finishing and Coiling

[0073] The reduction per pass is strictly controlled at 15%. The composite plate after intermediate rolling is reciprocated through the front and rear tension devices and is coiled when the thickness reaches the finished product thickness.

[0074] Step 7: Annealing of finished product

[0075] The rolled aluminum-copper composite material is subjected to a finished product vacuum annealing treatment at 430°C for 1.5 hours to eliminate the work hardening of the aluminum-copper composite material, thereby obtaining an ultra-thin aluminum-copper composite strip with an ultra-thin interface.

[0076] Figure 2 The cross-section electron microscope photo of the aluminum-copper composite strip obtained is shown in the figure. The photo shows that it is mainly composed of aluminum alloy matrix and copper matrix, with a very thin aluminum-copper composite interface in the middle. The copper foil layer thickness of the aluminum-copper composite strip obtained is 0.02mm, the aluminum alloy thin layer thickness is 0.20mm, the copper-aluminum thickness ratio is 1 / 10, and the aluminum-copper composite interface layer thickness is less than 0.01mm. The resistivity of the composite strip was tested, and the results showed that the conductivity of the composite material measured from the aluminum alloy side was 61.5% IACS.

[0077] Example 3

[0078] Step 1: Material Preparation

[0079] The same method as in Example 1 was used to prepare aluminum alloy ingots and copper ingots.

[0080] The cast aluminum alloy and copper ingots were respectively subjected to billet rolling, and after intermediate rolling and finish rolling, the aluminum alloy plate thickness δ1 = 6.5 mm ± 0.3 mm and the copper plate δ2 = 0.15 mm ± 0.03 mm were obtained. They were uniformly cut into plates with a width of 400 mm and a length of 2000 mm.

[0081] Put the prepared plate into the leveling machine for plate leveling, and use the angle grinder to grind the surface, and the grinding direction of aluminum alloy and copper plates is consistent, reaching the surface roughness Ra≥3.2. Remove the surface oxide film, then use the washing liquid to remove surface impurities and oil, rinse the surface with clean water, dehydrate with alcohol, and dry with a hot air machine.

[0082] Step 2: Friction stir welding preform

[0083] The prepared aluminum-copper sheet is fixed to the friction stir welding platform. The welding direction is the width direction of the sheet. A welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid keyholes after welding. The aluminum sheet is on top and the copper sheet is on the bottom. The stirring head is pressed down to penetrate the copper sheet by 0.1mm. The stirring head is tilted at 2°, the stirring head speed is 800r / min, and the welding speed is 20mm / min. Stir friction welding is performed to complete the preforming of the aluminum-copper dissimilar metal composite sheet.

[0084] Step 3: Rolling the composite

[0085] The preformed aluminum-copper dissimilar metal composite sheet is placed in a rolling mill and rolled at a first rolling rate of 50% and a rolling speed of 10 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 3 mm.

[0086] Step 4: Friction stir welding connection

[0087] The two aluminum-copper composite plates that have completed rolling and cladding are connected end to end and fixed to the friction stir welding platform. The welding direction is the width direction of the plate, and a welding guide plate with the same thickness as the material to be welded is connected at the end of welding to avoid the appearance of keyholes after welding. The copper side of the composite plate is on the top and the aluminum side is on the bottom. The stirring head is pressed down to less than 0.05mm of the composite plate thickness, the stirring head is tilted at 2°, the stirring head speed is 800r / min, and the welding speed is 20mm / min for friction stir welding connection.

[0088] Step 5: Intermediate rolling

[0089] The aluminum-copper dissimilar metal composite sheet connected by friction stir welding is put into a rolling mill and rolled at a pass reduction rate of 40% and a rolling speed of 50 cm / s until the thickness of the aluminum-copper dissimilar metal composite sheet reaches about 1 mm.

[0090] Step 6: Finishing and Coiling

[0091] The reduction per pass is strictly controlled at 20%. The composite plate after intermediate rolling is reciprocated through the front and rear tension devices and is coiled when the thickness reaches the finished product thickness.

[0092] Step 7: Annealing of finished product

[0093] The rolled aluminum-copper composite material is subjected to a finished product vacuum annealing treatment at 400°C for 2 hours to eliminate the work hardening of the aluminum-copper composite material, thereby obtaining an ultra-thin aluminum-copper composite strip with an ultra-thin interface.

[0094] Figure 3 The cross-section electron microscope photo of the aluminum-copper composite strip obtained. The photo shows that it is mainly composed of aluminum alloy matrix and copper matrix, with a very thin aluminum-copper composite interface in the middle. The copper foil layer thickness of the aluminum-copper composite strip obtained is 0.02mm, the aluminum alloy thin layer thickness is 0.18mm, the copper-aluminum thickness ratio is 1 / 9, and the aluminum-copper composite interface layer thickness is less than 0.01mm. The resistivity of the composite strip was tested, and the results showed that the conductivity of the composite material measured from the aluminum alloy side was 61.4% IACS.

[0095] Comparative Example 1

[0096] The composite strip was prepared by the same preparation method as in Example 1, except that erbium was not added to the aluminum alloy.

[0097] Figure 4 This is a cross-sectional electron microscope photo of the aluminum-copper composite strip obtained. The photo shows that it is mainly composed of an aluminum alloy matrix and a copper matrix, with an extremely thin aluminum-copper composite interface in the middle. The composite interface is jagged, indicating that the strength of the two metals in the interface layer is quite different, and there are some scratches on the aluminum alloy matrix, which shows that the strength of the aluminum alloy is relatively low. The thickness of the copper foil layer is 0.024mm, the thickness of the aluminum alloy thin layer is 0.216mm, the copper-aluminum thickness ratio is 1 / 9, and the thickness of the aluminum-copper composite interface layer is less than 0.01mm. The resistivity of the composite strip was tested, and the results showed that the conductivity of the composite material measured from the aluminum alloy side was 57.3% IACS.

Claims

1. An ultra-thin aluminum-copper composite strip with an ultra-thin interface, characterized in that: The strip is made of aluminum foil and copper foil by rolling. The aluminum foil contains 0.2%-0.4% magnesium, 0.01%-0.03% erbium, and the remainder is aluminum. The copper foil is electronic oxygen-free copper with a purity of ≥99.99%. The thickness of the composite strip interface layer is ≤0.01mm, the copper-aluminum thickness ratio is 1 / 9~1 / 11, and the thickness of the strip is 0.18~0.24 mm.

2. The method for preparing an ultra-thin aluminum-copper composite strip with an ultra-thin interface as claimed in claim 1, characterized in that: The method comprises the following steps: I. Smelting and casting aluminum alloy ingots and pure copper ingots, and rolling the aluminum alloy ingots and copper ingots into thin plates; wherein the composition of the aluminum alloy ingot is: 0.2%-0.4% magnesium, 0.01%-0.03% erbium, and the balance is aluminum; the composition of the copper ingot is electronic oxygen-free copper with a purity of ≥99.99%; rolling the aluminum alloy ingot into aluminum foil with a thickness of 6.2-6.8 mm, and rolling the copper ingot into copper foil with a thickness of 0.12-0.18 mm; II. Take aluminum foil and copper foil of the same width and length, level them first and then grind the surface; the surface is polished by a brush machine, pneumatic sandblasting or an angle grinder equipped with a turbine, and the surface roughness reaches Ra≥3.2; then clean the surface, stack the aluminum foil and copper foil, and stir friction welding preform one end; stir friction welding is performed with the aluminum foil on top and the copper foil on the bottom, the stirring head is pressed down to less than 0.05~0.1 mm of the composite plate thickness, the stirring head is tilted at an angle of 1~2°, the stirring head speed is 800~1500r / min, and the welding speed is 20~40mm / min; III. The preformed aluminum-copper material prepared in step II is rolled and composited, the first pass of the composite rolling reduction rate is not less than 50%, the rolling speed is not more than 10cm / s, and the total reduction rate after rolling is 60~80%; IV. The aluminum-copper composite plates are connected end to end by friction stir welding to form a long plate; the copper side of the friction stir welding is on the top and the aluminum side is on the bottom, the stirring head is pressed down to a thickness less than 0.02~0.05 mm of the composite plate, the inclination angle of the stirring head is 1~2°, the stirring head speed is 800~1500 r / min, and the welding speed is 20~40 mm / min; V. Perform intermediate rolling forming on the connected aluminum-copper composite long plates to complete further strip forming; the intermediate rolling forming pass reduction rate is not less than 40%, and the rolling speed is not more than 50cm / s; VI. Finish rolling and coiling the aluminum-copper composite strip, with the reduction rate of the finishing rolling forming pass not exceeding 20%, and adding front and rear tension devices, reciprocating rolling the composite strip after intermediate rolling, and coiling it after reaching the finished product thickness of 0.18~0.24 mm; VII. The aluminum-copper composite strip that has been finished rolled and coiled is subjected to final annealing, wherein the final annealing is vacuum annealing at 400-450°C for 1-2 hours to obtain an ultra-thin aluminum-copper composite strip with an ultra-thin interface.

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