Aluminum-based composite copper foil and preparation method and application thereof

Abstract

The invention provides an aluminum-based composite copper foil and a preparation method and application thereof, and belongs to the field of metal materials. The method comprises the following steps: removing an aluminum foil surface oxide layer; an Al-Zn-Zr alloy layer, an Al-Zr gradient layer and a nano-porous copper layer are sequentially deposited on the two faces of the aluminum foil through multi-target magnetron sputtering, and a three-layer composite transition layer is obtained; a copper plating layer is formed on the surface of the transition layer through a water electroplating method; electrically depositing a chromium-containing passivation layer on the surface of the copper plating layer; and carrying out micro-rolling extension treatment and pulse laser annealing treatment to obtain the aluminum-based composite copper foil. The aluminum-based composite copper foil is used as a flexible material for preparing electronic or new energy batteries or aerospace equipment. The aluminum-based composite copper foil prepared by the invention has the advantages of stable transition layer, high binding force, excellent folding resistance, high corrosion resistance and the like, and overcomes the defects of growth, warping cracking and the like of an aluminum-based layer and an ultrathin / ultra-thick copper plating layer; the brittle phase of the transition layer is inhibited, the elongation and the folding resistance are improved, and the stability of the self performance can be kept in an extremely severe environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal composite materials, and particularly relates to an aluminum-based composite copper foil, a preparation method thereof, and an application thereof. Background Art

[0002] Aluminum foil has advantages such as light weight, good airtightness and coating properties, and has been widely used in fields such as electronics, packaging, and construction. However, aluminum is a very active amphoteric metal with a high degree of oxygen affinity, and it is easy to form an oxide film on its surface. In addition, the aluminum foil has low strength and insufficient hardness, resulting in easy deformation and fracture, etc., thereby reducing the quality of the aluminum foil. To solve this problem, a copper layer is covered on the aluminum foil to form an aluminum-based composite copper foil, thereby improving its mechanical properties. The metal foil of aluminum-copper composite is formed by combining aluminum and copper through methods such as electroplating, cold rolling, continuous casting and rolling, and explosion welding. Among them, the aluminum foil is used as the substrate and the copper layer is used as the outer coating layer, which is a widely used aluminum-based composite copper foil. It has the advantages of both, such as the light weight characteristic of aluminum and the good electrical conductivity of copper. The aluminum-based composite copper foil has become the most commonly used and most important new advanced material due to its outstanding mechanical, physical properties, other comprehensive special properties and economy, etc.

[0003] However, since both aluminum and copper are metal materials, simply combining aluminum and copper easily results in the phenomenon of interface delamination, leading to unstable interfaces, and further affecting the performance of the final product.

[0004] Therefore, in existing research, a transition layer is provided between the aluminum foil substrate and the outer copper coating layer to enhance the bonding strength between the two. The transition layer is generally a single metal (such as copper, nickel) or a composite metal (such as copper + nickel) by magnetron sputtering. Although the interface bonding stability is improved to a certain extent, the interface bonding strength is still weak. The transition layer has the disadvantages of brittle phases, and the foil layer is prone to growth and warping and cracking, with weak mechanical properties and poor corrosion resistance, etc. In addition, the existing aluminum-based composite copper foil cannot maintain the stability of its own performance in extremely harsh environments such as high temperature, high humidity, and low temperature, thereby limiting the application range. For example, in fields such as aerospace, 5G communication, and new energy vehicles, the stability requirements of aluminum-based composite copper foil in extreme environments are much higher than those in conventional application environments. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an aluminum-based composite copper foil, a preparation method thereof, and an application thereof, aiming to solve at least one technical problem in the background art.

[0006] The present invention is implemented as follows:

[0007] A preparation method of an aluminum-based composite copper foil, which includes:

[0008] Providing an aluminum foil and removing the oxide layer on its surface;

[0009] The Al-Zn-Zr alloy layer, Al-Zr gradient layer, and nanoporous copper layer are sequentially deposited on both sides of the aluminum foil by multi-target magnetron sputtering to obtain a three-layer composite transition layer;

[0010] A copper plating layer is formed on the surface of the transition layer by the hydroelectroplating method;

[0011] A chromium-containing passivation layer is electrodeposited on the surface of the copper plating layer;

[0012] The aluminum-based composite copper foil is obtained after composite strengthening treatment;

[0013] Among them, the composite strengthening treatment includes micro-rolling extension treatment and pulsed laser annealing treatment.

[0014] Preferably, when forming the Al-Zr gradient layer by multi-target magnetron sputtering, N2 with a preset flow rate is introduced to generate ZrN nanoparticles in the Al-Zr gradient layer.

[0015] Preferably, the proportion of the ZrN nanoparticles is 5wt%-10wt%; the size of the ZrN nanoparticles is ≤10nm.

[0016] Preferably, the Al-Zn-Zr alloy layer contains components with the following atomic percentages: Zn 20at%-30at%, Zr 5at%-10at%, and the balance is Al; the thickness of the Al-Zn-Zr alloy layer is 100nm-200nm.

[0017] Preferably, in the Al-Zr gradient layer, the Zr atomic content linearly decreases from 20at% to 0 in the direction from the Al-Zn-Zr alloy layer to the nanoporous copper layer; the thickness of the Al-Zr gradient layer is 100nm-200nm.

[0018] Preferably, the porosity of the nanoporous copper layer is 20%-30%, the pore diameter is 10nm-50nm, and the thickness is 50nm-100nm.

[0019] Preferably, in the hydroelectroplating method, the hydroelectroplating solution contains the following components:

[0020] 180g / L - 220g / L of CuSO4, 80g / L - 120g / L of H2SO4, 50ppm - 80ppm of Cl - And a composite additive;

[0021] The composite additive includes 0.1g / L - 0.3g / L of PEG-6000, 0.05g / L - 0.1g / L of thiourea derivative, and 1ppm - 5ppm of nano-SiO2;

[0022] The thickness of the copper plating layer is 0.5μm - 15μm.

[0023] Preferably, the passivation solution used in electro-depositing the chromium-containing passivation layer includes the following components: 3 g / L - 5 g / L of Cr 3+ , 10 mL / L - 20 mL / L of silane coupling agent, and its pH is 3.5 - 4.5;

[0024] The passivation solution further includes 0.5 wt% - 1.0 wt% of trivalent cerium salt.

[0025] Preferably, the method for removing the oxide layer on the surface of the aluminum foil is: using an Ar / O2 mixed gas to perform double-sided plasma cleaning on the aluminum foil with a thickness of 9 μm - 200 μm;

[0026] Among them, for the aluminum foil with a thickness of 9 μm - 50 μm, the power of double-sided plasma cleaning is 400 W - 600 W; for the aluminum foil with a thickness of 50 μm - 200 μm, the power of double-sided plasma cleaning is 600 W - 800 W.

[0027] Preferably, the specific operation of the micro-rolling extension is: performing roll pressing deformation at room temperature, and the deformation amount is 5% - 15%;

[0028] The pulsed laser annealing is scanned using fiber laser, and the energy density is 1 J / cm 2 -5 J / cm 2 , the pulse width is 10 ns - 100 ns, and the scanning speed is 1 m / s - 5 m / s.

[0029] The second aspect of the present invention provides an aluminum-based composite copper foil prepared by the above preparation method.

[0030] The third aspect of the present invention provides an application of an aluminum-based composite copper foil prepared by the above preparation method. The aluminum-based composite copper foil is used as a flexible material required in electronics, new energy batteries, or aerospace equipment, including but not limited to LED flexible light strip boards, 5G communication equipment, new energy vehicle batteries, wearable electronic devices, aerospace equipment, etc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention prepares an aluminum-based composite copper foil, which has the advantages of a stable transition layer, high bonding strength, excellent folding resistance, strong corrosion resistance, etc., and solves the defects such as the growth and warping and cracking of the aluminum base layer and ultra-thin / ultra-thick copper plating layer; inhibits the brittle phase of the transition layer, improves the elongation and folding resistance; and can maintain the stability of its own performance in extremely harsh environments. Furthermore, it expands the application fields and scenarios of the material.

[0033] 2. The present invention composes a transition layer by magnetron sputtering and depositing an Al-Zn-Zr alloy layer, an Al-Zr gradient layer, and a nanoporous copper layer, achieving atomic-level interlocking, which is beneficial to enhancing the interfacial bonding between the subsequent copper plating layer and the substrate aluminum foil.

[0034] 3. During the process of sputtering and depositing the Al-Zr gradient layer in the present invention, a trace amount of N2 is introduced to inhibit the Cu-Al interdiffusion, significantly reducing the galvanic corrosion rate.

[0035] 4. Trivalent Ce ions are added to the passivation solution in the present invention. The Ce 3+ ions migrate to repair microcracks, improving the mechanical properties of the product.

[0036] 5. The present invention adopts a combined composite strengthening treatment of micro-rolling extension and pulsed laser annealing, which can eliminate the interfacial residual stress, and thereby indirectly improve the properties of the product such as strength, corrosion resistance, and fold resistance.

[0037] 6. The aluminum foil substrate is pretreated by double-sided plasma cleaning in the present invention, reducing the regeneration of the aluminum foil surface oxide layer, removing the surface oxides, and enhancing its antioxidant ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of the aluminum-based composite copper foil of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] The structure of the aluminum-based composite copper foil of the present invention is as Figure 1 shown; the aluminum-based composite copper foil includes an aluminum foil 1, an Al-Zn-Zr alloy layer 2, an Al-Zr gradient layer 3, a nanoporous copper layer 4, a copper plating layer 5, and a passivation layer 6. Specifically, the aluminum-based composite copper foil includes a set of aluminum foils 1 in the middle and copper plating layers 5 on both sides of the aluminum foil 1; a composite transition layer is provided between the aluminum foil 1 and the copper plating layer 5; along the direction from the aluminum foil 1 to the copper plating layer 5, the transition layer includes an Al-Zn-Zr alloy layer 2, an Al-Zr gradient layer 3, and a nanoporous copper layer 4 stacked in sequence; a corrosion protection layer, the passivation layer 6, is provided on the surface of the copper plating layer 5.

[0041] A preparation method of an aluminum-based composite copper foil includes steps S1-S5.

[0042] S1. Surface pretreatment of the aluminum foil;

[0043] Using an aluminum foil with a thickness of 9 μm - 200 μm and a purity of ≥99.7% as the substrate, the aluminum foil is subjected to double-sided plasma cleaning with an Ar / O2 mixed gas to remove surface oxides and reduce the regeneration of the aluminum foil surface oxide layer; among them, for aluminum foils with a thickness of 9 μm - 50 μm, the power of double-sided plasma cleaning is 400 W - 600 W; for aluminum foils with a thickness of 50 μm - 200 μm, the power of double-sided plasma cleaning is 600 W - 800 W. The ratio of the Ar / O2 mixed gas can be adjusted as needed. In the following examples, the volume ratio of Ar:O2 = 4:1 is used for illustration, but it is not limited to this ratio, and other unlisted mixing ratios are also applicable.

[0044] S2. Prepare the transition layer;

[0045] An Al-Zn-Zr alloy layer, an Al-Zr gradient layer, and a nanoporous copper layer are sequentially deposited on both sides of the aluminum foil by multi-target magnetron sputtering to obtain a three-layer composite transition layer; in a specific implementation, magnetron sputtering deposition of the composite transition layer can achieve atomic-level interlocking, which is beneficial to enhancing the interfacial bonding between the subsequent copper coating and the substrate aluminum foil.

[0046] Among them, the Al-Zn-Zr alloy layer contains the following components in atomic percentages: Zn 20 - 30 at%, Zr 5 - 10 at%, and the balance is Al; the thickness of the Al-Zn-Zr alloy layer is 50 nm - 100 nm; [[ID=IO]]

[0047] The thickness of the Al-Zr gradient layer is 100 nm - 200 nm, and the Zr atomic content linearly decreases from 20 at% to 0 in the direction from the Al-Zn-Zr alloy layer to the nanoporous copper layer; when forming the Al-Zr gradient layer by multi-target magnetron sputtering, N2 with a flow rate of 5 sccm - 10 sccm is introduced, and then ZrN nanoparticles (size ≤ 10 nm) are generated in the Al-Zr gradient layer to form Al-Zr-ZrN, and the proportion of ZrN nanoparticles is 5 wt% - 10 wt%; in a specific implementation, Al-Zr-ZrN can inhibit Cu-Al interdiffusion and reduce the galvanic corrosion rate.

[0048] The porosity of the nanoporous copper layer is 20% - 30%, the pore diameter is 10 nm - 50 nm, and the thickness is 50 nm - 100 nm.

[0049] S3. Prepare the copper coating;

[0050] A copper coating is formed on the surface of the transition layer by the hydroelectroplating method, with a thickness of 0.5 μm - 15 μm, a grain size ≤ 500 nm, and an internal stress ≤ 100 MPa;

[0051] The electroplating solution contains the following components:

[0052] CuSO4 of 180 g / L - 220 g / L, H2SO4 of 80 g / L - 120 g / L, Cl of 50 ppm - 80 ppm - and a composite additive; the composite additive includes PEG - 6000 of 0.1 g / L - 0.3 g / L, a thiourea derivative of 0.05 g / L - 0.1 g / L, and nano - SiO2 of 1 ppm - 5 ppm;

[0053] Functions of the composite additive: Nano - SiO2 serves as a nucleation site to refine grains, making the grain size ≤ 500 nm; the thiourea derivative inhibits internal stress, making it ≤ 100 MPa; in specific implementations, the thiourea derivative uses thiourea or its derivatives permitted in the art, such as thiourea, dimethylthiourea, ethylthiourea, phenylthiourea, thiourea phosphate, etc. In the following examples, thiourea is used for illustration, but it is not limited to this thiourea derivative, and other unlisted thiourea derivatives are equally applicable.

[0054] S4. Prepare a passivation layer;

[0055] Perform passivation treatment on the copper plating surface, specifically, a chromium - containing passivation layer is prepared by electrodeposition;

[0056] The passivation solution includes the following components: Cr of 3 g / L - 5 g / L 3+ 、10 mL / L - 20 mL / L of a silane coupling agent, and its pH is 3.5 - 4.5; in specific implementations, the passivation solution also includes 0.5 wt% - 1.0 wt% of a trivalent cerium salt. Ce 3+ Ion migration can repair microcracks and further improve the mechanical properties of the product. Trivalent cerium salts in the art can be used, such as CeCl3, Ce(NO3)3, etc. In the following examples, Ce(NO3)3 is used, but it is not limited to this trivalent cerium salt, and other unlisted trivalent cerium salts are equally applicable; Cr 3+ Use chromium salts permitted in the art, such as chromium chloride, chromium nitrate, chromium sulfate, etc. In the following examples, Cr 3+ uses chromium chloride, but it is not limited to this chromium salt, and other unlisted chromium salts are equally applicable; the silane coupling agent uses any silane coupling agent permitted in the art, which is used to improve the adhesion, thermal / chemical stability, and corrosion resistance of the passivation layer. In the following examples, KH - 550 (γ - aminopropyltriethoxysilane) is used for illustration, but it is not limited to this silane coupling agent, and other unlisted silane coupling agents are equally applicable.

[0057] S5. Composite strengthening treatment;

[0058] Successively perform micro - rolling and stretching treatment and pulsed laser annealing treatment to obtain an aluminum - based composite copper foil, whose structure is as Figure 1As shown in the figure, it includes an aluminum foil 1, an Al-Zn-Zr alloy layer 2, an Al-Zr gradient layer 3, a nanoporous copper layer 4, a copper plating layer 5, and a passivation layer 6.

[0059] The micro-rolling and extension treatment is as follows: roll pressing deformation is carried out at room temperature, and the deformation amount is 5%-15% to improve the interfacial density; the pulsed laser annealing is scanned by a fiber laser, and the energy density is 1 J / cm 2 -5 J / cm 2 , the pulse width is 10 ns - 100 ns, and the scanning speed is 1 m / s - 5 m / s to eliminate the interfacial residual stress.

[0060] In specific implementation, the relationship between the deformation amount of micro-rolling and extension, the energy density of pulsed laser annealing, and the interfacial residual stress is shown in Table 1.

[0061] Table 1

[0062] Deformation amount (%) <![CDATA[Energy density (J / cm 2 )]]> Residual stress (MPa) 5-8 1-2 ≤50 8-12 2-3 ≤30 12-15 3-5 ≤10

[0063] Example 1

[0064] A preparation method of an aluminum-based composite copper foil, the steps are as follows:

[0065] S1. Use an Ar / O2 mixed gas (Ar:O2 = 4:1) to perform double-sided plasma cleaning on the aluminum foil (thickness = 25 μm), and the power is 450 W;

[0066] S2. Use multi-target magnetron sputtering to first deposit an Al-Zn-Zr alloy layer with a thickness of 50 nm on both sides of the surface-treated aluminum foil. The composition of the Al-Zn-Zr alloy layer is 75 at% Al - 20 at% Zn - 5 at% Zr; then deposit an Al-Zr gradient layer with a thickness of 100 nm, and the Zr atom content in the Al-Zr gradient layer linearly decreases from 20 at% to 0; finally deposit a nanoporous copper layer with a thickness of 50 nm, and its porosity is 20% and the pore diameter is 10 nm;

[0067] S3. Prepare an electroplating solution: 180 g / L CuSO4, 80 g / L H2SO4, 50 ppm Cl - , 0.1 g / L - PEG-6000, 0.05 g / L thiourea, and 1 ppm of nano-SiO2; use electroplating to form a copper plating layer with a thickness of 2 μm on the surface of the transition layer, and the current density is 12 A / dm 2 , and the thickness uniformity is ±2.8%;

[0068] S4. Prepare a passivation solution with a pH of 3.5: 4 g / L of CrCl3, 15 mL / L of silane coupling agent (KH-550), and obtain a chromium-containing passivation layer with a thickness of 150 nm through electrodeposition (6 V / 45 s);

[0069] S5. First, perform rolling deformation at room temperature with a deformation amount of 5%; then, use a 1064 nm fiber laser for scanning with an energy density of 1 J / cm 2 , a pulse width of 10 ns, and a scanning speed of 1 m / s.

[0070] Example 2

[0071] The difference between this example and Example 1 lies in the different thicknesses of the aluminum foil and the copper coating. The thickness of the aluminum foil is 100 μm (the power during double-sided plasma cleaning is 700 W), and the thickness of the copper layer is 10 μm. Other preparation processes and conditions are the same as those in Example 1.

[0072] Example 3

[0073] The difference between this example and Example 1 lies in the different thicknesses of the aluminum foil and the copper coating. The thickness of the aluminum foil is 50 μm (the power during double-sided plasma cleaning is 600 W), and the thickness of the copper layer is 6 μm. Other preparation processes and conditions are the same as those in Example 1.

[0074] Example 4

[0075] The difference between this example and Example 1 lies in the different thicknesses of the aluminum foil and the copper coating. The thickness of the aluminum foil is 200 μm (the power during double-sided plasma cleaning is 800 W), and the thickness of the copper layer is 15 μm. Other preparation processes and conditions are the same as those in Example 1.

[0076] Example 5

[0077] The difference between this example and Example ① lies in that during the process of sputtering and depositing the Al-Zr gradient layer in S2, a trace amount of N2 is introduced at a flow rate of 5 sccm to generate ZrN nanoparticles in the Al-Zr gradient layer. Other preparation processes and conditions are the same as those in Example 1.

[0078] Example 6

[0079] The difference between this example and Example 5 lies in that during the process of sputtering and depositing the Al-Zr gradient layer in S2, the flow rate of N2 introduced is 8 sccm. Other preparation processes and conditions are the same as those in Example ^.

[0080] Example 7

[0081] The difference between this example and Example 5 lies in that during the process of sputtering and depositing the Al-Zr gradient layer in S2, the flow rate of N2 introduced is 10 sccm. Other preparation processes and conditions are the same as those in Example 5.

[0082] Example 8

[0083] The difference between this example and Example 1 is that the composition of the Al-Zn-Zr alloy layer obtained in S2 is 70at% Al - 20at% Zn - 10at% Zr, and the other preparation processes and conditions are the same as those in Example 1.

[0084] Example 9

[0085] The difference between this example and Example 1 is that the composition of the Al-Zn-Zr alloy layer obtained in S2 is 65at% Al - 30at% Zn - 5at% Zr, and the other preparation processes and conditions are the same as those in Example 1.

[0086] Example 10

[0087] The difference between this example and Example 1 lies in the dosage of the composite additive in the electroplating solution in S3; the dosage of the composite additive in S3 of this example is: 0.2 g / L PEG-6000, 0.07 g / L thiourea, and 3 ppm of nano-SiO2; the other preparation processes and conditions are the same as those in Example 1.

[0088] Example 11

[0089] The difference between this example and Example 1 lies in the dosage of the composite additive in the electroplating solution in S3; the dosage of the composite additive in S3 of this example is: 0.3 g / L PEG-6000, 0.1 g / L thiourea, and 5 ppm of nano-SiO2; the other preparation processes and conditions are the same as those in Example 1.

[0090] Example 12

[0091] The difference between this example and Example 1 lies in the dosage of the passivation solution in S4; the dosage of the passivation solution in S4 of this example is: 3 g / L of CrCl3, 10 mL / L of KH-550; the other preparation processes and conditions are the same as those in Example 1.

[0092] Example 13

[0093] The difference between this example and Example 1 lies in the dosage of the passivation solution in S4; the dosage of the passivation solution in S4 of this example is: 5 g / L of CrCl3, 20 mL / L of KH-550; the other preparation processes and conditions are the same as those in Example 1.

[0094] Example 14

[0095] The difference between this example and Example 1 lies in the parameters of S5; specifically, in this example, S5 is as follows: first, roll pressing deformation is carried out at room temperature, and the deformation amount is 10%; then, scanning is carried out using a 1064 nm fiber laser, with an energy density of 3 J / cm 2 , the pulse width is 50 ns, and the scanning speed is 3 m / s; the other preparation processes and conditions are the same as those in Example 1.

[0096] Example 15

[0097] The difference between this example and Example 1 lies in the parameters of S5; specifically, in this example, S5 is as follows: first, roll deformation is carried out at room temperature, and the deformation amount is 15%; then, scanning is carried out using a 1064 nm fiber laser, the energy density is 5 J / cm 2 , the pulse width is 50 ns, and the scanning speed is 5 m / s; other preparation processes and conditions are the same as those in Example 1.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that: step S5 is deleted, that is, the composite strengthening treatment step of the combination of micro-rolling extension treatment and pulsed laser annealing treatment is not carried out, and other preparation processes and conditions are the same as those in Example 1.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that: step S4 is deleted, that is, there is no passivation layer, and other preparation processes and conditions are the same as those in Example 1.

[0102] Comparative Example 3

[0103] The difference between this comparative example and Example 1 is that: the deposition step of the Al-Zn-Zr alloy layer in S2 is deleted, that is, there is no Al-Zn-Zr alloy layer in the transition layer, and other preparation processes and conditions are the same as those in Example 1.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 1 is that: the deposition step of the Al-Zr gradient layer in S2 is deleted, that is, there is no Al-Zr gradient layer in the transition layer, and other preparation processes and conditions are the same as those in Example 1.

[0106] Comparative Example 5

[0107] The difference between this comparative example and Example 1 is that: the deposition step of the nanoporous copper layer in S2 is deleted, that is, there is no nanoporous copper layer in the transition layer, and other preparation processes and conditions are the same as those in Example 1.

[0108] Comparative Example 6

[0109] The difference between this comparative example and Example 1 is that: when magnetron sputtering the Al-Zr gradient layer in S2, the Zr content is uniform and consistent, rather than decreasing linearly, and other preparation processes and conditions are the same as those in Example 1.

[0110] Comparative Example 7

[0111] The difference between this comparative example and Example 1 is that: the composite additive in the electroplating solution in S3 is deleted, and other preparation processes and conditions are the same as those in Example 1.

[0112] Comparative Example 8

[0113] The difference between this comparative example and Example 1 is that the nanoporous copper layer in S2 is adjusted to a conventional nanocopper layer, that is, without a porous structure, and other preparation processes and conditions are the same as those in Example 1.

[0114] Comparative Example 9

[0115] The difference between this comparative example and Example 1 is that the order of the Al-Zn-Zr alloy layer and the Al-Zr gradient layer in S2 is reversed. Specifically, along the direction from the aluminum foil to the copper plating layer, the transition layer includes an Al-Zr gradient layer, an Al-Zn-Zr alloy layer, and a nanoporous copper layer stacked in sequence, and other preparation processes and conditions are the same as those in Example 1.

[0116] I. Performance tests, as shown in Table 3;

[0117] Perform performance tests on the aluminum-based composite copper foils prepared in Examples 1 to 15 and Comparative Examples 1 to 9; specifically including:

[0118] (1) Bonding strength, and the tensile strength test is used to measure the strength required for interface delamination;

[0119] (2) Resistivity, which is measured using a metal foil resistivity meter;

[0120] (3) Corrosion resistance; the copper-accelerated acetate spray test (CASS test) method is used to detect for 800 h, and the corrosion resistance is classified according to the rating standard in Table 2;

[0121] (4) Folding test, under the conditions of room temperature (25°C ± 10°C), a bending radius R of 0.08 mm, and a bending angle of ±180°, a rubber roller of about 3 kg is used to apply a load, and after unfolding, the load is applied repeatedly by folding, and an optical microscope is used to observe whether there are cracks, and the number of folds when fracture is observed is counted.

[0122] Table 2

[0123] Level Percentage of defective area Phenomenon description 1 25％～50％ Severe corrosion phenomenon 2 10％～25％ Matrix metal corrosion 3 5％～10％ Very thick corrosion product layer or pitting, with deep pitting 4 2.5％～5％ Thick corrosion product layer or pitting 5 1.0％～2.5％ Corrosion products or pitting, distributed on the entire specimen surface 6 0.5％～1.0％ Severe loss of luster, or local surface with a thin layer of corrosion products or pitting 7 0.25％～0.5％ Severe loss of luster or extremely slight corrosion products appear 8 0.1％～0.25％ Severe discoloration or extremely slight corrosion 9 ≤0.1％ Slight to moderate discoloration 10 0％ No change

[0124] Table 3

[0125]

[0126]

[0127] As can be seen from the data in Table 3, the aluminum-based composite copper foil prepared in the embodiment of the present invention has a bonding strength greater than 120 MPa; a resistivity ≤ 1.9 μΩ·cm, a corrosion resistance ≥ 9 levels, and the number of folding times observed at fracture is greater than 80 times, indicating that the aluminum-based composite copper foil prepared in the present invention has the advantages of a stable transition layer, high bonding strength, excellent folding resistance, and strong corrosion resistance.

[0128] In Examples 1 to 4, copper coatings and aluminum foils with different thicknesses were used. As can be seen from the data in Table 3, regardless of thickness, the metal foils obtained by the combination of the two have excellent mechanical properties, a stable interface, and a corrosion resistance that can reach 9 levels.

[0129] Comparing Example 5 with Example 1, it can be seen that ZrN particles are formed in the Al-Zr gradient layer, and the bonding strength and folding resistance of the finally obtained aluminum-based composite copper foil are significantly improved, the resistivity decreases slightly, and the corrosion resistance is improved to 10 levels.

[0130] Comparing Examples 6 and 7 with Example 5, it can be seen that as the amount of N2 increases, that is, the content of ZrN particles formed in the Al-Zr gradient layer increases, the bonding strength is greater than 140 MPa, the resistivity ≤ 1.7 μΩ·cm, the corrosion resistance is 10 levels, and the number of folding times observed at fracture is greater than 100 times, that is, the properties such as bonding strength, folding resistance, corrosion resistance, and resistivity remain good.

[0131] Comparing Examples 8 and 9 with Example 1, it can be seen that by adjusting the atomic content of each component in the Al-Zn-Zr alloy layer, the bonding strength is greater than 130 MPa, the resistivity ≤ 1.9 μΩ·cm, the corrosion resistance ≥ 9 levels, and the number of folding times observed at fracture is greater than 90 times, that is, the properties such as bonding strength, folding resistance, corrosion resistance, and resistivity remain good.

[0132] Comparing Examples 10 and 11 with Example 1, it can be seen that by adjusting the amount of the composite additive in the electroplating solution, the bonding strength is greater than 140 MPa, the resistivity ≤ 1.7 μΩ·cm, the corrosion resistance is 9 levels, and the number of folding times observed at fracture is greater than 90 times, that is, the properties such as bonding strength, folding resistance, corrosion resistance, and resistivity remain good.

[0133] Comparing Examples 12 and 13 with Example 1, it can be seen that by adjusting the amount of each component in the passivation solution of the electroplating solution, the bonding strength is greater than 130 MPa, the resistivity ≤ 1.9 μΩ·cm, the corrosion resistance is 9 levels, and the number of folding times observed at fracture is greater than 80 times, that is, the properties such as bonding strength, folding resistance, corrosion resistance, and resistivity remain good.

[0134] Comparing Example 14, Example 15 with Example 1, it can be seen that by adjusting the parameters of the composite strengthening treatment, the bonding strength is greater than 140 MPa, the resistivity is ≤ 1.6 μΩ·cm, the corrosion resistance is grade 9, and the number of folding times at break is observed to be not less than 100 times. That is, the properties such as bonding strength, folding resistance, corrosion resistance, and resistivity are all maintained well.

[0135] Comparing Comparative Example 1 to Comparative Example 5 with Example 1, it can be seen that in the process of preparing the aluminum-based composite copper foil of the present invention, deleting any one of the steps of composite strengthening, depositing the Al-Zn-Zr alloy layer, depositing the Al-Zr gradient layer, depositing the nanoporous copper layer, and preparing the passivation layer will significantly reduce the bonding strength, folding resistance, and corrosion resistance, and reduce the mechanical properties. The resistivity fluctuates up and down due to the deletion of additives or treatment steps.

[0136] Comparing Comparative Example 6 with Example 1, it can be seen that when the Zr content is not set to decrease linearly during the magnetron sputtering of the Al-Zr gradient layer, the bonding strength, folding resistance, and corrosion resistance all decrease to a certain extent, and the resistivity increases.

[0137] Comparing Comparative Example 7 with Example 1, it can be seen that if the composite additive is not added to the electroplating solution in S3, the change in resistivity is not obvious, but the bonding strength and folding resistance both decrease to a certain extent, and the corrosion resistance decreases significantly.

[0138] Comparing Comparative Example 8 with Example 1, it can be seen that when the nanoporous copper layer in S2 is adjusted to a conventional nanocopper layer without a porous structure, the change in resistivity is not obvious, but the bonding strength and corrosion resistance both decrease to a certain extent, and the folding resistance decreases significantly.

[0139] Comparing Comparative Example 9 with Example 1, it can be seen that when the order of the Al-Zn-Zr alloy layer and the Al-Zr gradient layer in S2 is swapped, the change in resistivity is not obvious, but the bonding strength, corrosion resistance, and folding resistance all decrease to a certain extent.

[0140] II. Influence of extreme environments on the properties of aluminum-based composite copper foils;

[0141] Under different extreme environments, the aluminum-based composite copper foils prepared in Examples 1 to 15 and Comparative Examples 1 to 9 were subjected to performance tests and observations to test the stability of the properties of the aluminum-based composite copper foils, including the bonding strength retention rate, resistivity change, passivation layer cracking, and interface delamination.

[0142] The extreme environments include the following situations:

[0143] Extreme environment A is: 85°C / 85% RH damp heat environment + salt spray cycle (72 h salt spray → 24 h drying), 100 cycles, and the test results are shown in Table 4;

[0144] Extreme environment B is as follows: After thermal aging at 300 °C for 500 h, the test results are shown in Table 5;

[0145] Extreme environment C is as follows: Thermal shock at -40 °C for 100 cycles, and the test results are shown in Table 6;

[0146] Extreme environment D is as follows: Heat treatment at 500 °C for 200 h + liquid nitrogen impact at -196 °C, and the test results are shown in Table 7;

[0147] Among them, the bonding strength retention rate (%) = 100 * bonding strength after extreme environment test / initial bonding strength;

[0148] Resistivity change (%) = 100 * (resistivity after extreme environment test - initial resistivity) / initial resistivity; The passivation layer cracking and interface delamination conditions were observed using an optical microscope.

[0149] Table 4

[0150]

[0151] Table 5

[0152]

[0153]

[0154] Table 6

[0155]

[0156] Table 7

[0157]

[0158] From the data in Tables 4 to 7, it can be seen that for the aluminum-based composite copper foil prepared in the embodiments of the present invention, under extreme environments such as damp heat + salt spray cycle, thermal aging, thermal shock, heat treatment + liquid nitrogen impact, etc., the bonding strength retention rate ≥ 90%. The resistivity change ≤ 3%, and there is no cracking in the passivation layer and no delamination at the interface.

[0159] For the aluminum-based composite copper foils prepared in Comparative Examples 1 to 9, under various extreme environments, the bonding strength retention rate and resistivity change are greater than those in the embodiments of the present invention, and at least one of the crack conditions such as passivation layer cracking and interface delamination will occur, indicating that under extreme environments, the interfaces of the aluminum-based composite copper foils prepared in Comparative Examples 1 to 7 are significantly unstable.

[0160] As can be seen from Tables 3 to 7, the aluminum-based composite copper foil prepared in the embodiments of the present invention has good mechanical properties, electromagnetic properties and corrosion resistance in a conventional environment, and can still maintain excellent stability in different extreme environments. It can be used as a flexible material in electronic devices, new energy batteries or aerospace equipment, including but not limited to LED flexible light strip boards, 5G communication devices, new energy vehicle batteries, wearable electronic devices, aerospace equipment, etc.

[0161] The above embodiments only represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A preparation method of an aluminum-based composite copper foil, characterized in that, The preparation method includes: providing an aluminum foil and removing the oxide layer on its surface; successively depositing an Al-Zn-Zr ternary alloy layer, an Al-Zr intermetallic compound gradient layer, and a nanoporous copper layer on both sides of the aluminum foil by multi-target magnetron sputtering to obtain a three-layer composite transition layer; forming a copper plating layer on the surface of the transition layer by electroplating; electrodepositing a chromium-containing passivation layer on the surface of the copper plating layer; obtaining the aluminum-based composite copper foil after composite strengthening treatment; wherein, the composite strengthening treatment includes micro-rolling and stretching treatment and pulsed laser annealing treatment.

2. The preparation method of an aluminum-based composite copper foil according to claim 1, characterized in that When forming the Al-Zr gradient layer by multi-target magnetron sputtering, N2 with a preset flow rate is introduced to generate ZrN nanoparticles in the Al-Zr gradient layer, and the proportion of the ZrN nanoparticles is 5wt%-10wt%; the size of the ZrN nanoparticles is ≤10nm; In the Al-Zr gradient layer, the content of Zr atoms linearly decreases from 20at% to 0 in the direction from the Al-Zn-Zr alloy layer to the nanoporous copper layer; the thickness of the Al-Zr gradient layer is 100nm-200nm.

3. The preparation method of an aluminum-based composite copper foil according to claim 1, characterized in that, The Al-Zn-Zr alloy layer contains the following components in atomic percentages: Zn 20at%-30at%, Zr 5at%-10at%, and the balance is Al; the thickness of the Al-Zn-Zr alloy layer is 100nm-200nm.

4. The preparation method of an aluminum-based composite copper foil according to claim 1, wherein The porosity of the nanoporous copper layer is 20%-30%, the pore diameter is 10nm-50nm, and the thickness is 50nm-100nm.

5. The preparation method of an aluminum-based composite copper foil according to claim 1, characterized in that In the electroplating method, the electroplating solution contains the following components: CuSO4 of 180 g / L - 220 g / L, H2SO4 of 80 g / L - 120 g / L, Cl of 50 ppm - 80 ppm - and a composite additive; The composite additive includes 0.1g / L-0.3g / L of PEG-6000, 0.05g / L-0.1g / L of thiourea derivative, and 1ppm-5ppm of nano-SiO2; The thickness of the copper plating layer is 0.5μm-15μm.

6. The preparation method of an aluminum-based composite copper foil according to claim 1, characterized in that, The passivation solution used in electro-depositing a chromium-containing passivation layer includes the following components: 3 g / L - 5 g / L of Cr 3+ , 10 mL / L - 20 mL / L of a silane coupling agent, and its pH is 3.5 - 4.5; The passivation solution further includes 0.5wt%-1.0wt% of trivalent cerium salt.

7. The preparation method of an aluminum-based composite copper foil according to claim 1, wherein The method for removing the oxide layer on the surface of the aluminum foil is: performing double-sided plasma cleaning on the aluminum foil with a thickness of 9μm-200μm using an Ar / O2 mixed gas; wherein, for the aluminum foil with a thickness of 9μm-50μm, the power of double-sided plasma cleaning is 400W-600W; for the aluminum foil with a thickness of 50μm-200μm, the power of double-sided plasma cleaning is 600W-800W.

8. The preparation method of an aluminum-based composite copper foil according to claim 1, characterized in that, The specific operation of the micro-rolling and stretching is: performing rolling deformation at room temperature, and the deformation amount is 5%-15%; The pulsed laser annealing is performed by scanning with a fiber laser, and the energy density is 1 J / cm 2 -5 J / cm 2 , the pulse width is 10 ns - 100 ns, and the scanning speed is 1 m / s - 5 m / s.

9. An aluminum-based composite copper foil prepared by the preparation method according to any one of claims 1 to 8.

10. Use of an aluminum-based composite copper foil prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The aluminum-based composite copper foil is used as a flexible material required in electronics, new energy batteries, or aerospace equipment.

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