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

Abstract

This invention provides an aluminum-based composite copper foil, its preparation method, and its application, belonging to the field of metallic materials. The method includes: removing the oxide layer from the surface of the aluminum foil; sequentially depositing an Al-Zn-Zr alloy layer, an Al-Zr gradient layer, and a nanoporous copper layer on both sides of the aluminum foil using multi-target magnetron sputtering to obtain a three-layer composite transition layer; forming a copper plating layer on the surface of the transition layer using electroplating; electrodepositing a chromium-containing passivation layer on the surface of the copper plating layer; and obtaining the aluminum-based composite copper foil after micro-rolling and pulsed laser annealing. This aluminum-based composite copper foil is used as a flexible material required for the preparation of electronic or new energy batteries or aerospace equipment. This invention prepares an aluminum-based composite copper foil with advantages such as a stable transition layer, high bonding strength, excellent folding resistance, and strong corrosion resistance, solving defects such as growth and warping cracking of the aluminum base layer and ultra-thin / ultra-thick copper plating; suppressing the brittle phase of the transition layer, improving elongation and folding resistance, and maintaining stable performance even in extremely harsh environments.

Description

Technical Field

[0001] This invention belongs to the field of metal composite materials technology, and specifically relates to an aluminum-based composite copper foil, its preparation method, and its application. Background Technology

[0002] Aluminum foil, with its advantages of being lightweight, airtight, and having good covering properties, has been widely used in electronics, packaging, construction, and other fields. However, aluminum is a highly reactive amphoteric metal with a strong affinity for oxygen, easily forming an oxide film on its surface. Furthermore, aluminum foil has low strength and insufficient hardness, leading to easy deformation and breakage, thus reducing its quality. To address this issue, a copper layer is coated onto the aluminum foil to form aluminum-aluminum composite copper foil, thereby improving its mechanical properties. Aluminum-copper composite foils are made by bonding aluminum and copper together through methods such as electroplating, cold rolling, casting, and explosive welding. Among these methods, aluminum foil as the substrate and a copper layer as the outer coating are the most widely used aluminum-based composite copper foils, combining the advantages of both, such as the lightweight properties of aluminum and the good electrical conductivity of copper. Due to its outstanding mechanical and physical properties, other comprehensive special properties, and economic efficiency, aluminum-based composite copper foil has become the most commonly used and important new high-grade material.

[0003] However, since aluminum and copper are both metals, simply combining them can easily lead to interface delamination, resulting in interface instability and affecting the performance of the final product.

[0004] To address this, existing research incorporates a transition layer between the aluminum foil substrate and the outer copper coating to enhance their bonding strength. This transition layer is typically a single metal (such as copper or nickel) or a composite metal (such as copper + nickel) sputtered by magnetron sputtering. While this improves the interfacial bonding stability to some extent, the interfacial bonding strength remains relatively weak. The transition layer suffers from the disadvantage of a brittle phase, and the foil layer is prone to growth, warping, and cracking, exhibiting weak mechanical properties and poor corrosion resistance. Furthermore, existing aluminum-based composite copper foils cannot maintain stable performance under extreme conditions such as high temperature, high humidity, and low temperature, thus limiting their application scope. For example, in fields such as aerospace, 5G communication, and new energy vehicles, the stability requirements of aluminum-based composite copper foils under extreme environments are far higher than those in conventional application environments. Summary of the Invention

[0005] Therefore, the present invention aims to provide an aluminum-based composite copper foil, its preparation method and application, in order to solve at least one technical problem in the background art.

[0006] This invention is implemented as follows:

[0007] A method for preparing an aluminum-based composite copper foil, comprising:

[0008] Provide aluminum foil and remove its surface oxide layer;

[0009] An Al-Zn-Zr alloy layer, an Al-Zr gradient layer, and a nanoporous copper layer were sequentially deposited on both sides of an aluminum foil using 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 electroplating.

[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] The composite strengthening treatment includes micro-rolling and pulsed laser annealing.

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

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

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

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

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

[0019] Preferably, the electroplating solution in the electroplating method comprises the following components:

[0020] 180g / L-220g / L CuSO4, 80g / L-120g / L H2SO4, 50ppm-80ppm Cl - And compound additives;

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

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

[0023] Preferably, the passivation solution used in electrodepositing the chromium-containing passivation layer comprises the following components: 3 g / L-5 g / L of Cr 3+ 10 mL / L-20 mL / L silane coupling agent with a pH of 3.5-4.5;

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

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

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

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

[0028] The pulsed laser annealing is performed using a fiber laser with an energy density of 1 J / cm². 2 -5J / cm 2 The pulse width is 10ns-100ns, and the scan speed is 1m / s-5m / s.

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

[0030] The third aspect of this invention provides an application of an aluminum-based composite copper foil prepared by the above-described method. This aluminum-based composite copper foil is used as a flexible material required in electronic or new energy batteries or aerospace equipment, including but not limited to LED flexible light strips, 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. This invention prepares an aluminum-based composite copper foil with advantages such as a stable transition layer, high bonding strength, excellent folding resistance, and strong corrosion resistance. It solves defects such as growth, warping, and cracking of aluminum substrates and ultra-thin / ultra-thick copper plating; it suppresses brittle phases in the transition layer, improving elongation and folding resistance; and it can maintain stable performance even in extremely harsh environments. This expands the application fields and scenarios of the material.

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

[0034] 3. During the sputtering deposition of the Al-Zr gradient layer in this invention, a trace amount of N2 is introduced to suppress Cu-Al interdiffusion and significantly reduce the galvanic corrosion rate.

[0035] 4. This invention adds trivalent Ce ions to the passivation solution. 3+ Ion migration repairs microcracks and improves product mechanical properties.

[0036] 5. The present invention employs a composite strengthening treatment combining micro-rolling and pulsed laser annealing, which can eliminate residual stress at the interface and thereby indirectly improve the product's strength, corrosion resistance, flexural strength, and other properties.

[0037] 6. The present invention performs double-sided plasma cleaning pretreatment on the aluminum foil substrate to reduce the regeneration of the oxide layer on the aluminum foil surface, remove surface oxides, and improve its oxidation resistance. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the aluminum-based composite copper foil of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] The structure of the aluminum-based composite copper foil of the present invention is as follows: Figure 1 As 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 an aluminum foil 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 layers 5; along the direction from the aluminum foil 1 to the copper plating layer 5, the transition layer includes the Al-Zn-Zr alloy layer 2, the Al-Zr gradient layer 3, and the nanoporous copper layer 4 stacked sequentially; an anti-corrosion passivation layer 6 is provided on the surface of the copper plating layer 5.

[0041] A method for preparing aluminum-based composite copper foil, comprising steps S1-S5.

[0042] S1. Aluminum foil surface pretreatment;

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

[0044] S2. Prepare the transition layer;

[0045] A three-layer composite transition layer was obtained by sequentially depositing an Al-Zn-Zr alloy layer, an Al-Zr gradient layer, and a nanoporous copper layer on both sides of an aluminum foil using multi-target magnetron sputtering. In practice, 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 plating layer and the substrate aluminum foil.

[0046] The Al-Zn-Zr alloy layer contains the following atomic percentage components: Zn 20-30 at%, Zr 5-10 at%, with Al as the balance; the thickness of the Al-Zn-Zr alloy layer is 50 nm-100 nm.

[0047] The Al-Zr gradient layer has a thickness of 100nm-200nm, and the Zr atomic content decreases linearly from 20at% to 0 from the Al-Zn-Zr alloy layer to the nanoporous copper layer. During the formation of the Al-Zr gradient layer by multi-target magnetron sputtering, N2 with a flow rate of 5sccm-10sccm is introduced, thereby generating ZrN nanoparticles (≤10nm in size) in the Al-Zr gradient layer, forming Al-Zr-ZrN, with the ZrN nanoparticles accounting for 5wt%-10wt%. In specific implementations, Al-Zr-ZrN can suppress Cu-Al interdiffusion and reduce the galvanic corrosion rate.

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

[0049] S3. Prepare copper plating layer;

[0050] A copper plating layer is formed on the surface of the transition layer using an electroplating method. The thickness of the plating layer is 0.5μm-15μm, the grain size is ≤500nm, and the internal stress is ≤100MPa.

[0051] The electroplating solution contains the following components:

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

[0053] The functions of the composite additive are as follows: nano-SiO2 acts as a nucleation site to refine the grains, resulting in a grain size ≤500nm; the thiourea derivative suppresses internal stress, making it ≤100MPa; in specific implementations, the thiourea derivative is any thiourea or its derivative permitted in the art, such as thiourea, dimethylthiourea, ethylthiourea, phenylthiourea, thiourea phosphate, etc. The following examples use thiourea as an example, but are not limited to this thiourea derivative, and other unlisted thiourea derivatives are also applicable.

[0054] S4. Prepare the passivation layer;

[0055] Passivation treatment is performed on the surface of the copper plating layer, specifically by electrodeposition to obtain a chromium-containing passivation layer;

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

[0057] S5, composite reinforcement treatment;

[0058] Aluminum-based composite copper foil is obtained by sequentially performing micro-rolling and pulsed laser annealing processes, and its structure is as follows: Figure 1As shown, it includes aluminum foil 1, Al-Zn-Zr alloy layer 2, Al-Zr gradient layer 3, nanoporous copper layer 4, copper plating layer 5, and passivation layer 6.

[0059] The micro-rolling and stretching process involves: roll deformation at room temperature with a deformation amount of 5%-15% to improve interface density; pulsed laser annealing is performed using a fiber laser with an energy density of 1 J / cm². 2 -5J / cm 2 The pulse width is 10ns-100ns, the scan speed is 1m / s-5m / s, and the residual stress at the interface is eliminated.

[0060] In practice, the relationship between the deformation of micro-rolling, the energy density of pulsed laser annealing, and the residual stress at the interface 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 method for preparing aluminum-based composite copper foil, comprising the following steps:

[0065] S1. Double-sided plasma cleaning of aluminum foil (thickness = 25μm) is performed using Ar / O2 mixed gas (Ar:O2 = 4:1) at a power of 450W.

[0066] S2. Using multi-target magnetron sputtering, a 50 nm thick Al-Zn-Zr alloy layer is first deposited 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, a 100 nm thick Al-Zr gradient layer is deposited, in which the Zr atom content decreases linearly from 20 at% to 0. Finally, a 50 nm thick nanoporous copper layer is deposited with a porosity of 20% and a pore size of 10 nm.

[0067] S3. Preparation of electroplating solution: 180g / L CuSO4, 80g / L H2SO4, 50ppm Cl - The mixture contained 0.1 g / L PEG-6000, 0.05 g / L thiourea, and 1 ppm nano-SiO2; a 2 μm thick copper plating layer was formed on the surface of the transition layer using an electroplating method with a current density of 12 A / dm³. 2 Thickness uniformity ±2.8%;

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

[0069] S5. First, roll deformation is performed at room temperature with a deformation amount of 5%; then, scanning is performed using a 1064nm fiber laser with an energy density of 1J / cm². 2 The pulse width is 10 ns and the scan rate is 1 m / s.

[0070] Example 2

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

[0072] Example 3

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

[0074] Example 4

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

[0076] Example 5

[0077] The difference between this embodiment and Example 1 is that: during the S2 sputtering deposition of the Al-Zr gradient layer, 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 in Example 1.

[0078] Example 6

[0079] The difference between this embodiment and embodiment 5 is that the N2 flow rate is 8 sccm during the S2 sputtering deposition of the Al-Zr gradient layer, while the other preparation processes and conditions are the same as in embodiment 5.

[0080] Example 7

[0081] The difference between this embodiment and embodiment 5 is that the N2 flow rate is 10 sccm during the S2 sputtering deposition of the Al-Zr gradient layer, while the other preparation processes and conditions are the same as in embodiment 5.

[0082] Example 8

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

[0084] Example 9

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

[0086] Example 10

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

[0088] Example 11

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

[0090] Example 12

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

[0092] Example 13

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

[0094] Example 14

[0095] The difference between this embodiment and Embodiment 1 lies in the parameters of S5; in this embodiment, S5 specifically involves: first, performing roll forming deformation at room temperature with a deformation amount of 10%; then, scanning with a 1064nm fiber laser at an energy density of 3J / cm². 2 The pulse width was 50 ns and the scan rate was 3 m / s; other preparation processes and conditions were the same as in Example 1.

[0096] Example 15

[0097] The difference between this embodiment and Embodiment 1 lies in the parameters of S5; in this embodiment, S5 specifically involves: first, performing roll forming deformation at room temperature with a deformation amount of 15%; then, scanning with a 1064nm fiber laser at an energy density of 5J / cm². 2 The pulse width was 50 ns and the scan rate was 5 m / s; other preparation processes and conditions were the same as in Example 1.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that step S5, namely the composite strengthening treatment step combining micro-rolling and pulsed laser annealing, is omitted. The other preparation processes and conditions are the same as in Example 1.

[0100] Comparative Example 2

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

[0102] Comparative Example 3

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

[0104] Comparative Example 4

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

[0106] Comparative Example 5

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

[0108] Comparative Example 6

[0109] The difference between this comparative example and Example 1 is that the Zr content is uniform and consistent during magnetron sputtering of the Al-Zr gradient layer in S2, rather than decreasing linearly. Other preparation processes and conditions are the same as 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 removed, while the other preparation processes and conditions are the same as 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 nanoporous copper layer, i.e., without a porous structure. The other preparation processes and conditions are the same as 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 the Al-Zr gradient layer, the Al-Zn-Zr alloy layer and the nanoporous copper layer stacked in sequence. The other preparation processes and conditions are the same as in Example 1.

[0116] I. Performance test results are shown in Table 3;

[0117] The performance of aluminum-based composite copper foils prepared in Examples 1 to 15 and Comparative Examples 1 to 9 was tested; specifically including:

[0118] (1) Bond strength: The strength required for interface delamination is tested using a tensile strength test;

[0119] (2) Resistivity was measured using a metal foil resistivity meter;

[0120] (3) Corrosion resistance; The copper accelerated acetic acid salt spray test (CASS test) was used to test the corrosion resistance for 800 hours, and the rating criteria in Table 2 were used to classify the corrosion resistance.

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

[0122] Table 2

[0123] level Defect area ratio Phenomenon description 1 25％～50％ Severe corrosion 2 10％～25％ Base metal corrosion 3 5％～10％ Very thick corrosion product layer or pitting corrosion, with deep pitting corrosion. 4 2.5％～5％ Thick corrosion product layer or pitting corrosion 5 1.0％～2.5％ Corrosion products or pitting are distributed throughout the entire sample surface. 6 0.5％～1.0％ Severe loss of gloss, or localized thin layer of corrosion products or pitting corrosion on the surface. 7 0.25％～0.5％ Severe loss of luster or the appearance of very slight corrosion products 8 0.1％～0.25％ Severe discoloration or very slight corrosion 9 ≤0.1％ Slight to moderate discoloration 10 0％ No change

[0124] Table 3

[0125]

[0126]

[0127] As shown in Table 3, the aluminum-based composite copper foil prepared in the embodiments of the present invention has a bonding strength greater than 120 MPa, a resistivity ≤ 1.9 μΩ·cm, a corrosion resistance ≥ 9, and is observed to have more than 80 folds at breakage. This indicates that the aluminum-based composite copper foil prepared in the present invention has the advantages of a stable transition layer, high bonding force, excellent folding resistance, and strong corrosion resistance.

[0128] Examples 1 to 4 use copper plating and aluminum foil of different thicknesses. As shown in Table 3, regardless of thickness, the composite metal foil has excellent mechanical properties, stable interface, and corrosion resistance of up to level 9.

[0129] Comparing Example 5 with Example 1, it can be seen that forming ZrN particles in the Al-Zr gradient layer significantly improves the bonding strength and folding resistance of the final aluminum-based composite copper foil, slightly reduces the resistivity, and improves the corrosion resistance to level 10.

[0130] Comparing Examples 6 and 7 with Example 5, it can be seen that as the amount of N2 increases, i.e. the content of ZrN particles formed in the Al-Zr gradient layer increases, the bonding strength is greater than 140 MPa, the resistivity is ≤1.7 μΩ·cm, the corrosion resistance is grade 10, and the number of folds at break is greater than 100. That is, the bonding strength, folding resistance, corrosion resistance, resistivity and other properties are all maintained well.

[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 is ≤1.9 μΩ·cm, the corrosion resistance is ≥9, and the number of folds at fracture is greater than 90, that is, the bonding strength, folding resistance, corrosion resistance, resistivity and other properties are all well maintained.

[0132] Comparing Examples 10 and 11 with Example 1, it can be seen that by adjusting the amount of composite additives in the electroplating solution, the bonding strength is greater than 140 MPa, the resistivity is ≤1.7 μΩ·cm, the corrosion resistance is level 9, and the number of folds at breakage is greater than 90, that is, the bonding strength, folding resistance, corrosion resistance, resistivity and other properties are all maintained well.

[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 in the electroplating solution, the bonding strength is greater than 130 MPa, the resistivity is ≤1.9 μΩ·cm, the corrosion resistance is level 9, and the number of folds at breakage is greater than 80. That is, the bonding strength, folding resistance, corrosion resistance, resistivity and other properties are all maintained well.

[0134] Comparing Examples 14 and 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 level 9, and the number of folds at break is not less than 100. That is, the bonding strength, folding resistance, corrosion resistance, resistivity and other properties are all maintained well.

[0135] Comparing Comparative Examples 1 to 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 step of composite strengthening, depositing Al-Zn-Zr alloy layer, depositing Al-Zr gradient layer, depositing nanoporous copper layer, or preparing passivation layer will significantly reduce the bonding strength, folding resistance, corrosion resistance, and mechanical properties, while the resistivity will fluctuate due to the deletion of additives or processing 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 magnetron sputtering of Al-Zr gradient layers, the bonding strength, flexural strength, and corrosion resistance all decrease to a certain extent, while the resistivity increases.

[0137] Comparing Comparative Example 7 with Example 1, it can be seen that if no composite additive is added to the electroplating solution in S3, the resistivity does not change significantly, but the bonding strength and flexural strength 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 nanoporous copper layer without a porous structure, the resistivity does not change significantly, but the bonding strength and corrosion resistance decrease to a certain extent, and the folding resistance decreases significantly.

[0139] Comparing Comparative Example 9 with Example 1, it can be seen that changing the order of the Al-Zn-Zr alloy layer and the Al-Zr gradient layer in S2 does not significantly change the resistivity, but the bonding strength, corrosion resistance, and flexural strength all decrease to some extent.

[0140] II. The impact of extreme environments on the performance of aluminum-based composite copper foil;

[0141] The performance of aluminum-based composite copper foils prepared in Examples 1 to 15 and Comparative Examples 1 to 9 was tested and observed under different extreme environments. The stability of the performance of the aluminum-based composite copper foils was tested, including the retention rate of bonding strength, the change of resistivity, the cracking of the passivation layer and the delamination of the interface.

[0142] Extreme environments include the following situations:

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

[0144] Extreme environment B is: after thermal aging at 300℃ for 500h, the test results are shown in Table 5;

[0145] Extreme environment C is: 100 cycles of thermal shock at -40℃. The test results are shown in Table 6.

[0146] Extreme environment D is: 500℃ / 200h heat treatment ±196℃ liquid nitrogen impact. The test results are shown in Table 7.

[0147] Wherein, 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; passivation layer cracking and interface delamination were observed using an optical microscope.

[0149] Table 4

[0150]

[0151] Table 5

[0152]

[0153]

[0154] Table 6

[0155]

[0156] Table 7

[0157]

[0158] As shown in Tables 4 to 7, the aluminum-based composite copper foil prepared in the embodiments of the present invention maintains a bonding strength retention rate of ≥90% under extreme environments such as damp heat + salt spray cycling, thermal aging, alternating hot and cold shock, and heat treatment + liquid nitrogen shock. The resistivity change is ≤3%, and the passivation layer shows no cracking and the interface shows no delamination.

[0159] The aluminum-based composite copper foils prepared in Comparative Examples 1 to 9 exhibited greater strength retention and resistivity changes than those in the embodiments of the present invention under various extreme environments, and at least one of the following crack conditions—passivation layer cracking or interface delamination—was observed. This indicates that the aluminum-based composite copper foils prepared in Comparative Examples 1 to 7 showed significant instability at the interface under extreme environments.

[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 under normal conditions, and can still maintain excellent stability under 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 strips, 5G communication equipment, new energy vehicle batteries, wearable electronic devices, aerospace equipment, etc.

[0161] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for producing an aluminum-based composite copper foil, characterized by, The preparation method comprises: S1, providing an aluminum foil, removing the surface oxide layer thereof; S2, using a multi-target magnetron sputtering to sequentially deposit an Al-Zn-Zr alloy layer, an Al-Zr gradient layer and a nano-porous copper layer on both sides of the aluminum foil to obtain a three-layer composite transition layer; when the multi-target magnetron sputtering forms the Al-Zr gradient layer, a preset flow of N2 is introduced to generate ZrN nanoparticles in the Al-Zr gradient layer, the ZrN nanoparticles account for 5wt%-10wt%; the ZrN nanoparticles have a size of ≤10nm; in the Al-Zr gradient layer, the Zr atomic content linearly decreases from 20at% in the Al-Zn-Zr alloy layer to 0 in the nano-porous copper layer; the thickness of the Al-Zr gradient layer is 100nm-200nm; the nano-porous copper layer has a porosity of 20%-30%, a pore size of 10nm-50nm and a thickness of 50nm-100nm; S3. Forming a copper plating layer on the surface of the transition layer by a water electroplating method; the water electroplating solution in the water electroplating method comprises the following components: 180 g / L-220 g / L of CuSO4, 80 g / L-120 g / L of H2SO4, 50 ppm-80 ppm of Cl - and a composite additive; the composite additive comprises 0.1 g / L-0.3 g / L of PEG-6000, 0.05 g / L-0.1 g / L of a thiourea derivative, and 1 ppm-5 ppm of nano-SiO2; the thickness of the copper plating layer is 0.5 μm-15 μm; S4, electrodepositing a chromium-containing passivation layer on the surface of the copper plating layer; S5, obtaining the aluminum-based composite copper foil after composite strengthening treatment; The composite strengthening treatment comprises micro-rolling extension treatment and pulse laser annealing treatment.

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

3. The method for preparing an aluminum-based composite copper foil according to claim 1, characterized in that, The passivation solution used in the electrodeposition of the chromium-containing passivation layer comprises the following components: 3 g / L - 5 g / L Cr 3+ , 10 mL / L - 20 mL / L silane coupling agent, with a pH of 3.5 - 4.

5. The passivation solution further comprises 0.5wt%-1.0wt% of trivalent cerium salt.

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

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

6. An aluminum-based composite copper foil prepared by the preparation method of any one of claims 1 to 5.

7. Use of an aluminum-based composite copper foil produced by the production method according to any one of claims 1 to 5, characterized in that, The aluminum-based composite copper foil is used as a flexible material required in electronic or new energy batteries or aerospace equipment.

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