Copper-aluminum composite foil and preparation method therefor

Abstract

A copper-aluminum composite foil and a preparation method therefor. The preparation method comprises the following steps: S1, smelting an aluminum ingot and then pouring same into a preheated casting nozzle, and cooling and crystallizing cast molten aluminum until it is in a semi-molten state, so as to prepare a semi-molten aluminum material; preheating a copper material; contacting the surface of the semi-molten aluminum material with the surface of the copper material, and performing continuous cast rolling to prepare a composite mother blank with a thickness of 7.0-10.0 mm; S2, machining the composite mother blank into a blank with a thickness of 0.15-1.0 mm by means of cold rolling; S3, subjecting the blank to an annealing treatment at 190-300°C under the protection of an inert gas for 10-30 h, and S4, rolling the annealed blank foil to a thickness of 0.01-0.035 mm to prepare the foil. Further disclosed is a copper-aluminum composite foil prepared by the method. The thickness of the foil prepared by the preparation method for a copper-aluminum composite foil is smaller than that in the prior art.

Description

Copper-aluminum composite foil and preparation method thereof Technical Field

[0001] The invention relates to the field of copper-aluminum composite plates and strips, in particular to a copper-aluminum composite foil and a preparation method thereof. Background Art

[0002] Copper-aluminum composite foil is a copper-aluminum composite sheet with extremely small thickness.

[0003] Copper-aluminum composite foil has important applications in the electronics field. Its excellent electrical and thermal conductivity makes it suitable for manufacturing electronic component wires, circuit boards, and heat sinks. Copper-aluminum composite foil has superior electrical conductivity to pure aluminum foil, while its thermal conductivity is superior to pure copper foil. Therefore, it can optimize circuits and heat dissipation in electronic devices, improving their performance and reliability.

[0004] The current methods for producing copper-aluminum composite sheets include explosive composite, double-die casting, hydrostatic extrusion, electroplating process and continuous rolling. Among them, continuous rolling is a method for producing copper-aluminum composite sheets that is more energy-efficient and easier to control during the production process.

[0005] For example, CN108237151B discloses an ultra-thin copper-clad copper-aluminum composite material and its production method, which includes: compounding a layer of aluminum coating on the surface of the aluminum layer of the copper-aluminum composite plate to obtain a copper-aluminum composite billet, and cold rolling the billet; the state of the aluminum layer material of the copper-aluminum composite material is O state, the grade of the copper layer material is T2, and the aluminum layer material is a 1 series, 3 series or 8 series deformed aluminum alloy; the thickness of the copper-aluminum composite plate is 0.8 to 6.0 mm, and compounding a layer of aluminum coating on the surface of the aluminum layer of the copper-aluminum composite plate is specifically as follows: the aluminum layer of the copper-aluminum composite plate is contacted with a semi-molten aluminum alloy liquid, and then oxygen-free continuous casting and rolling is performed to obtain the copper-aluminum composite billet.

[0006] In order to reduce the thickness of copper-aluminum composite plates and produce copper-aluminum composite foils, Chinese patent publication number CN109078983B discloses a method for preparing ultra-thin copper-aluminum composite foils. The multi-pass rolling + intermediate annealing process avoids the shortcomings of high explosion energy and poor welding performance. The prepared copper-aluminum composite foil has a thickness of only 0.06 mm. The interface of the 0.06 mm thick copper-aluminum composite foil is metallurgically bonded, which can demonstrate the advantages of high electrical conductivity, high thermal conductivity, corrosion resistance, and low cost of aluminum-copper composite plates.

[0007] The problem with the existing technology is that the thickness of the copper-aluminum composite material obtained by continuous rolling is still not small enough and cannot be well applied in the electronics field.

[0008] Summary of the Invention

[0009] In order to solve the above technical problems, the purpose of the present invention is to provide a copper-aluminum composite foil and a preparation method thereof. The copper-aluminum composite foil has a thickness of 0.01-0.035 mm and can be used in the electronics field.

[0010] A method for preparing a copper-aluminum composite foil comprises the following steps: Step S1: Melting an aluminum ingot and pouring it into a preheated casting nozzle. The cast aluminum liquid is cooled and crystallized to a semi-molten state to produce a semi-molten aluminum material; the semi-molten aluminum material is brought into contact with the surface of a copper material and continuously cast and rolled to produce a composite mother billet with a thickness of 7.0-10.0 mm; Step S2: Cold-rolling the composite mother billet into a billet with a thickness of 0.15-1.0 mm. Step S3: Annealing the billet at 190-300°C under an inert gas atmosphere for 10-30 hours. Step S4: Rolling the annealed billet into a foil with a thickness of 0.01-0.035 mm to produce the foil material. In Step S4, the foil rolling speed is 300-1300 m / min, the foil rolling pressure is 130-190 tons, and the tension is 1400-2200 N.

[0011] As a preferred technical solution, in step S1 , the semi-molten aluminum material is in contact with both the upper and lower surfaces of the copper material.

[0012] As a preferred technical solution, after step S4, the foil is further slitting or trimming to obtain a finished product.

[0013] As a preferred technical solution, the grade of the aluminum ingot is 3003 or 8011, and the grade of the copper material is T2.

[0014] The present invention also provides a copper-aluminum composite foil material, which is prepared by adopting the preparation method of the copper-aluminum composite foil material.

[0015] As a preferred technical solution, the width of the foil is in the range of 800-1350 mm.

[0016] As a preferred technical solution, in the foil, the thickness of the intermetallic compound is 300-1000 nm.

[0017] As a preferred technical solution, the thickness of the copper layer accounts for 15%-40% of the thickness of the foil.

[0018] The beneficial effects of the present invention are:

[0019] A special annealing process is used, and compared with the existing technology, the annealing control is more precise, which reduces the thickness of the intermetallic compounds in the copper-aluminum composite foil. Combined with the foil rolling process, a thinner copper-aluminum composite foil can be rolled out, with a thickness range of 0.01-0.035mm. The lower thickness can bring better toughness, making the copper-aluminum composite foil of the present invention suitable for the electronics field;

[0020] The thickness of the intermetallic compound in the copper-aluminum composite foil of the present invention is 300-1000 nm, which is relatively low. The relatively low thickness of the intermetallic compound can also improve the toughness of the copper-aluminum composite foil and reduce the possibility of separation of the aluminum layer from the same layer during the bending process.

[0021] The copper-aluminum composite foil of the present invention has a width range of 800-1350 mm, which is relatively wide. Increasing the width range means improving the production efficiency of the copper-aluminum composite foil and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0023] FIG1 is a photograph showing the thickness of the intermetallic compound of Sample 1;

[0024] FIG2 is a photograph showing the thickness of the intermetallic compound of Sample 2;

[0025] FIG3 is a photograph showing the thickness of the intermetallic compound of sample 3. DETAILED DESCRIPTION

[0026] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0027] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0028] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0029] A method for preparing a copper-aluminum composite foil, comprising:

[0030] Example 1: Step S1, prepare an aluminum ingot, melt the aluminum ingot, refine it into 3003, pour it into a preheated casting nozzle, cool and crystallize the cast aluminum liquid to a semi-molten state, and obtain a semi-molten aluminum material; take a copper material with a grade of T2; contact the semi-molten aluminum material with the upper surface of the copper material, and perform continuous casting and rolling to obtain a 7.0 mm thick composite mother blank; the thickness of the copper layer accounts for 15% of the thickness of the composite mother blank.

[0031] Step S2: cold-rolling the composite mother billet into a billet with a thickness of 0.15 mm.

[0032] Step S3: Anneal the blank at 300°C under inert gas protection for 10 hours. Specific annealing steps: Employees inspect the blanks to ensure uniform color on both surfaces. Place the blanks in the annealing furnace, evacuate the furnace, and then fill it with nitrogen. After the furnace is filled with nitrogen, place the heating hood in place and begin heating. After heating to 300°C within 2 hours, anneal at this temperature for 10 hours. Stop heating, lift the heating hood, replace it with a cooling hood, cool to room temperature, lift the cooling hood, and then lift the blanks out of the annealing furnace.

[0033] Step S4: placing the annealed blank into a foil rolling device and rolling it to a thickness of 0.01 mm to obtain a foil material, wherein the thickness of the copper layer accounts for 15% of the thickness of the foil material; wherein the foil rolling speed is 1300 m / min, the foil rolling pressure is 190 tons, and the tension is 1400 N.

[0034] Step S5: trim the foil to obtain sample 1. The thickness and width of sample 1 are 0.010 mm and 940 mm respectively.

[0035] Example 2: Step S1, prepare an aluminum ingot, melt the aluminum ingot, refine it into 3003, pour it into a preheated casting nozzle, cool and crystallize the cast aluminum liquid to a semi-molten state, and obtain a semi-molten aluminum material; take a copper material with a grade of T2; contact the semi-molten aluminum material with the surface of the copper material, and perform continuous casting and rolling to obtain a composite mother blank with a thickness of 8.0 mm; the thickness of the copper layer accounts for 20% of the thickness of the composite mother blank.

[0036] Step S2: cold-rolling the composite mother billet into a billet with a thickness of 0.6 mm.

[0037] Step S3: Anneal the blank at 240°C under inert gas protection for 20 hours. Specific annealing steps: Employees conduct incoming material inspections on the blanks to ensure that the color of both surfaces is uniform. The blanks are placed in an annealing furnace, which is evacuated and then filled with nitrogen. After the filling is completed, a heating hood is placed and heating is started. The temperature is raised to 240°C within 2 hours and then maintained at this temperature for 20 hours. Heating is stopped, the heating hood is lifted, and a cooling hood is replaced. The blanks are cooled to room temperature, the cooling hood is lifted, and the blanks are then lifted out of the annealing furnace.

[0038] Step S4: rolling the annealed blank foil to a thickness of 0.025 mm to obtain a foil material, wherein the thickness of the copper layer accounts for 20% of the thickness of the foil material; the foil rolling speed is 650 m / min, the foil rolling pressure is 160 tons, and the tension is 1500 N.

[0039] Step S5: trim the foil to obtain sample 2. The thickness and width of sample 2 are 0.025 mm and 1350 mm, respectively.

[0040] Example 3: Step S1: The aluminum ingot is grade 8011, and the copper material is grade T2. The aluminum ingot is melted and poured into a preheated casting nozzle. The cast aluminum liquid is cooled and crystallized to a semi-molten state to produce a semi-molten aluminum material. The semi-molten aluminum material is brought into contact with the surface of the copper material and continuously cast and rolled to produce a 6.5 mm thick composite mother blank. The copper layer thickness accounts for 40% of the thickness of the composite mother blank.

[0041] Step S2: cold-rolling the composite mother billet into a billet with a thickness of 1.0 mm.

[0042] Step S3: Anneal the blank at 190°C under inert gas protection for 30 hours. Specific annealing steps: Employees conduct incoming material inspections on the blanks to ensure uniform color on both surfaces. The blanks are placed in an annealing furnace, which is evacuated and then filled with nitrogen. After the filling is complete, a heating hood is placed and heating is started. The temperature is raised to 190°C within 2 hours and then maintained at this temperature for 30 hours. Heating is stopped, the heating hood is lifted, and a cooling hood is replaced. The blanks are cooled to room temperature, the cooling hood is lifted, and the blanks are then removed from the annealing furnace.

[0043] Step S4: rolling the annealed blank foil to a thickness of 0.033 mm to obtain a foil material, wherein the thickness of the copper layer accounts for 40% of the thickness of the foil material; wherein the foil rolling speed is 400 m / min, the foil rolling pressure is 130 tons, and the tension is 2200 N.

[0044] Step S5: trim the foil to obtain sample 3. The thickness of sample 3 is 0.033 mm and the width is 1310 mm.

[0045] Example 4 differs from Example 1 in that, in step S1, the semi-molten aluminum material is brought into contact with the upper and lower surfaces of the copper material for continuous casting. The remaining steps are identical to those of Example 1, ultimately producing Sample 4. Sample 4 has a thickness of 0.011 mm and a width of 996 mm.

[0046] Example 5: This differs from Example 2 in that, in step S1, the semi-molten aluminum material is brought into contact with the upper and lower surfaces of the copper material for continuous casting. In step 4, the thickness of the foil after rolling is 0.024 mm. The remaining steps are identical to those of Example 2, ultimately producing Sample 5. Sample 5 has a thickness of 0.024 mm and a width of 800 mm.

[0047] Example 6: This differs from Example 3 in that, in step S1, the semi-molten aluminum material is brought into contact with the upper and lower surfaces of the copper material for continuous casting. In step 4, the thickness of the foil after rolling is 0.035 mm. The remaining steps are identical to those of Example 3, ultimately producing Sample 6. Sample 6 has a thickness of 0.035 mm and a width of 1100 mm.

[0048] Table 1 shows the thickness and width data for samples 1-6. Samples 1-6 have thicknesses ranging from 0.01-0.035 mm and widths ranging from 800-1350 mm. These thin, wide materials are suitable for electronics applications and have lower production costs than existing technologies.

[0049] Table 1. Thickness and width of samples 1-6

[0050] Bending Test: Samples 1-6 were cut into 200mm wide and 250mm long longitudinal specimens using a sampler. Five 15 x 150mm long longitudinal specimens were measured using a folding endurance tester, with the measurement angle set at 135° and the bending speed set at 175 times / minute. The test results are shown in Table 2. A higher average number of bends indicates greater sample toughness, a benefit of reduced sample thickness. Furthermore, greater toughness reduces the likelihood of separation between the aluminum and copper layers during bending, resulting in higher sample reliability. This is a reflection of the reduced intermetallic compound thickness in the sample.

[0051] Table 2. Bending test results of samples 1-6

[0052] 1-3 are photos of the thickness test of the intermetallic compound of samples 1-3 of the present invention. The thickness of the intermetallic compound in sample 1 of the present invention does not exceed 323.8nm, the thickness of the intermetallic compound in sample 2 does not exceed 401.9nm, and the thickness of the intermetallic compound in sample 3 does not exceed 815.0nm.

[0053] The thickness of the intermetallic compound of the ultra-thin copper-aluminum composite foil disclosed in the prior art publication number CN109078983B is close to 20 microns, indicating that the copper-aluminum composite foil of the present invention has a more excellent internal structure.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a copper-aluminum composite foil, characterized in that: The following steps are involved: Step S1, after melting the aluminum ingot, pour it into a preheated casting nozzle, cool the cast aluminum liquid and crystallize it to a semi-molten state to obtain a semi-molten aluminum material; contact the semi-molten aluminum material with the surface of the copper material, and perform continuous casting and rolling to obtain a composite mother billet with a thickness of 6.5-8.0 mm; Step S2, cold rolling the composite mother billet into a billet with a thickness of 0.15-1.0 mm; Step S3, annealing the blank at 190-300° C. under inert gas protection for 10-30 hours; Step S4: rolling the annealed blank foil to a thickness of 0.01-0.035 mm to obtain a foil material; the foil rolling speed is 400-1300 m / min, the foil rolling pressure is 130-190 tons, and the tension is 1400-2200 N.

2. The method for preparing a copper-aluminum composite foil according to claim 1, wherein: In step S1 , the semi-molten aluminum material is in contact with both the upper and lower surfaces of the copper material.

3. The method for preparing a copper-aluminum composite foil according to claim 1, wherein: After step S4, the foil is further cut or trimmed to obtain a finished product.

4. The method for preparing a copper-aluminum composite foil according to claim 1, wherein: The grade of the aluminum ingot is 3003 or 8011, and the grade of the copper material is T2.

5. A copper-aluminum composite foil, prepared by the method for preparing the copper-aluminum composite foil according to any one of claims 1 to 4.

6. A copper-aluminum composite foil as claimed in claim 5, characterized in that : The width of the foil is in the range of 800-1350 mm.

7. A copper-aluminum composite foil as claimed in claim 5, characterized in that : In the foil, the thickness of the intermetallic compound is 300-1000 nm.

8. The copper-aluminum composite foil according to claim 5, characterized in that: In the foil, the copper layer accounts for 15% to 40% of the foil thickness.

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