Iron-nickel alloy foil with copper-plated surface and preparation method thereof

Abstract

The preparation method comprises the steps that 1, an anode plate and a cathode roller are separately arranged in an electrolytic bath, the anode plate is made of iridium oxide titanium, the cathode roller is made of titanium, electrolyte is added into the electrolytic bath, first current is applied to the electrolyte, iron-nickel alloy is deposited on the surface of the cathode roller, and the iron-nickel alloy foil is obtained; 2, the iron-nickel alloy foil is moved into a copper plating tank containing a copper plating solution through a roll-to-roll process, second current is applied to the copper plating solution, surface copper plating is conducted, and the iron-nickel alloy foil subjected to copper plating is obtained; and 3, the copper-plated iron-nickel alloy foil is moved into a chromium anti-oxidation tank containing a Cr anti-rust solution through a roll-to-roll process to be subjected to Cr anti-rust treatment, and the iron-nickel alloy foil with the copper-plated surface is obtained through rolling. The surface copper-plated iron-nickel alloy foil provided by the invention solves the problem that the copper foil layer is easy to peel off due to insufficient binding force between the existing copper foil layer and the iron-nickel alloy foil layer.

Description

Technical Field

[0001] The invention belongs to the technical field of copper plating on the surface of an iron-nickel alloy foil, relates to a method for preparing the copper-plated iron-nickel alloy foil on the surface, and further relates to the copper-plated iron-nickel alloy foil on the surface obtained by the preparation method. Background Art

[0002] At present, copper foil is widely used in many fields such as lithium-ion battery negative electrode materials in the secondary battery industry, the electronic and electrical industry, the conductive circuits of printed circuit boards, or electronic equipment in the communications industry. It has the advantages of excellent conductivity and easy processing. However, copper foil also has obvious disadvantages: (1) It has relatively low mechanical strength and is easily deformed by external pressure; (2) It lacks corrosion resistance and is easily corroded; (3) It has poor heat resistance and is easily damaged at high temperatures.

[0003] Compared with copper foil, iron-nickel alloy foil has excellent physical properties such as high tensile strength and high stability after high temperature treatment, and iron-nickel alloy foil has strong magnetism, so it is expected to be used in various fields such as secondary battery industry, electric power industry and aerospace industry. However, since the conductivity of iron-nickel alloy foil is lower than that of copper foil, copper foil with better conductivity is currently mainly used in equipment that requires high-speed signal processing such as printed circuit boards, electronic equipment or high-frequency communication equipment.

[0004] In order to have the advantages of both iron-nickel alloy foil and copper foil so that they can be applied to more fields, researchers have proposed a method of copper plating on the surface of iron-nickel alloy foil to overcome the limitations of the above two films. However, the existing methods have the following technical difficulties: the interface bonding force between the iron-nickel alloy foil layer and the copper foil layer cannot be fully guaranteed; if the bonding force between the copper foil layer and the iron-nickel alloy foil layer is insufficient, the copper foil layer is prone to peeling under the influence of external impact or repeated high temperature, thereby reducing the reliability of the material. In particular, iron-nickel alloy and copper have different metallic properties. If the atomic diffusion at the interface is insufficient, the bonding force will be weakened. This problem of insufficient interface bonding force will cause cracks in the interface due to the accumulation of mechanical fatigue, or cause the copper foil layer to peel off at high temperature due to differences in thermal expansion coefficients. In addition, if tiny pores (porosity) are generated in the copper plating during the manufacturing process, it will make it more susceptible to external stress, making it difficult to maintain its stable performance for a long time. Summary of the invention

[0005] The first object of the present invention is to provide a method for preparing a copper-plated iron-nickel alloy foil, which solves the problem that the bonding force between the existing copper foil layer and the iron-nickel alloy foil layer is insufficient, thereby causing the copper foil layer to be easily peeled off.

[0006] The second object of the present invention is to provide a surface-plated copper-iron-nickel alloy foil obtained by the above preparation method.

[0007] The first technical solution adopted by the present invention is a method for preparing a copper-iron-nickel alloy foil with a surface plated thereon, characterized in that the specific method is as follows: Step 1, separately arranging an anode plate and a cathode roller in an electrolytic cell, wherein the material of the anode plate is iridium titanium oxide, and the material of the cathode roller is titanium, adding an electrolyte into the electrolytic cell, applying a first current into the electrolyte, and depositing an iron-nickel alloy on the surface of the cathode roller to obtain an iron-nickel alloy foil; Step 2, moving the iron-nickel alloy foil into a copper plating tank containing a copper plating solution through a roll-to-roll process, applying a second current to the copper plating solution to perform surface copper plating to obtain a copper-plated iron-nickel alloy foil; Step 3: Move the copper-plated iron-nickel alloy foil to a chromium anti-oxidation tank containing Cr anti-rust liquid through a roll-to-roll process for Cr anti-rust treatment, and roll it up to obtain the copper-plated iron-nickel alloy foil.

[0008] The present invention is also characterized in that: The electrolyte includes an iron solution, a nickel solution and a first additive; the electrolyte temperature is 45-65°C, and the first current density is 12-36A / dm 2 , electrolyte flow rate is 18~45m 3 / hr, the electrolyte pH is 2.0~3.0, and the solution pH is controlled by sodium bisulfate and sodium carbonate.

[0009] The iron solution is ferrous sulfate, and the concentration of the iron solution is 30~120g / L; the nickel solution is nickel sulfate, and the concentration of the nickel solution is 10~55g / L; The first additive includes an Fe reducing agent, a pH stabilizer, a conductive additive, a stress relaxant and a lubricant; The Fe reducing agent is any one of ascorbic acid, glucose, glycine or sodium gluconate, and the addition amount is 0.5~4.5g / L; The pH stabilizer is any one of glycine, sodium borate, boric acid, boron nitride or acetic acid, and the addition amount is 10.0~35.0g / L; The conductive additive is any one of sodium sulfate, sodium carbonate or sodium chloride, and the addition amount is 7.5~27.5g / L; The stress relaxant is any one of sodium allyl sulfonate, 2-propyl heptanol, sodium saccharin or bisbenzenesulfonimide, and the addition amount is 0.7~4.0g / L; The lubricant is any one of sodium dodecylbenzene sulfonate, sodium hydroxyethyl sulfonate or sodium succinate, and the added amount is 0.2-2.0 g / L.

[0010] The copper plating solution includes a copper sulfate solution and a second additive; The copper sulfate solution is prepared by mixing copper and sulfuric acid. The copper ion concentration in the copper plating solution is 40~55g / L, the sulfate ion concentration is 90~115g / L, and the hydrogen ion concentration is 1.15~1.30mol / L. The copper plating solution temperature is 40~45℃, and the second current density is 1~3A / dm 2 , copper plating liquid flow rate is 3~7 m 3 / hr.

[0011] The second additive includes a flattening agent, a speed reducer, a polishing agent, a surfactant and a uniform electrodeposition aid; The flattening agent is any one of sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, 2-mercaptobenzothiazole or 2-mercapto-5-benzimidazolesulfonic acid sodium salt, and the addition amount is 3.0~15.0mg / L; The moderator is any one of polyethylene glycol, nonylphenol polyethylene glycol, carboxymethyl cellulose or hydroxypropyl cellulose, and the addition amount is 7.0~20.0mg / L; The polishing agent is any one of 3-mercapto-1-propanesulfonic acid, o-ethylthiocarbonate-S-(3-sulfopropyl) ester sodium salt or 3-(N,N-dimethylthiocarbamoyl)-thiopropanesulfonic acid sodium salt, and the addition amount is 5.0~40.0mg / L; The surfactant is sodium alkylbenzene sulfonate, and the addition amount is 0.2~3.0g / L; The uniform electrodeposition aid is chromium chloride, and the addition amount is 3.0~30mg / L.

[0012] The Cr anti-rust liquid includes chromium trioxide and glucose, the addition amount of chromium trioxide is 1.1 kg / L, and the addition amount of glucose is 7.0 kg / L.

[0013] The temperature of Cr anti-rust liquid is 20~22℃, and the flow rate of Cr anti-rust liquid is 2~6 m 3 / hr, pH value of Cr rust preventive liquid is less than or equal to 3.5.

[0014] The second technical solution adopted by the present invention is that the copper-plated iron-nickel alloy foil is prepared by the above preparation method, the copper-plated iron-nickel alloy foil has a thickness of 8 μm, a surface roughness of Ra: 0.25-0.35 μm, a surface roughness of Rz: 1.15-1.30 μm, a tensile strength of 1320 MPa-1500 MPa at room temperature, an elongation of 2.30%-3.70% at room temperature, and a conductivity of 3.0×10 7 S / m and above.

[0015] The beneficial effects of the present invention are: (1) The preparation method of the surface-plated copper-iron-nickel alloy foil of the present invention can promote atomic diffusion between the copper foil layer and the iron-nickel alloy foil layer by simultaneously adding a certain proportion of surfactant and uniform electrodeposition auxiliary agent, thereby forming a stronger bond at the interface, enhancing the interfacial bonding force between the copper foil layer and the iron-nickel alloy foil layer, and preventing the copper foil layer from peeling off due to external stress or repeated high heat. It can achieve high tensile strength and high elongation, and still has relatively stable tensile strength and elongation after high-temperature heat treatment at 180°C. It is widely used in the fields of printed circuit boards, high-performance electronic equipment, high-frequency communication equipment, etc., and maintains ultra-high-speed signals and stable performance without reducing its own performance; (2) The copper-plated iron-nickel alloy foil prepared by the method of the present invention has a thickness of 8 μm, a surface roughness of Ra: 0.25-0.35 μm, a surface roughness of Rz: 1.15-1.30 μm, a tensile strength of 1320 MPa-1500 MPa at room temperature, and an elongation of 2.30%-3.70% at room temperature. After heat treatment at 180°C for 1 h, the copper-plated iron-nickel alloy foil has a tensile strength of 1230 MPa-1380 MPa, an elongation of 3.3%-4.7%, and a conductivity of 3×10 7 S / m and above. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of preparing electrolyte in the method for preparing surface copper-iron-nickel alloy foil of the present invention; Figure 2 It is a preparation flow chart of copper plating solution in the preparation method of the surface copper-plated iron-nickel alloy foil of the present invention; Figure 3 It is a flow chart of the preparation of Cr rust removal solution in the method for preparing the surface copper-plated iron-nickel alloy foil of the present invention; Figure 4 is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Example 1 of the present invention; Figure 5 is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Example 2 of the present invention; Figure 6 is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Example 3 of the present invention; Figure 7 is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Example 4 of the present invention; Figure 8 is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Example 5 of the present invention; Fig. 9 This is a SEM photo of the surface-plated copper-iron-nickel alloy foil prepared in Comparative Example 1 of the present invention; Fig.10 This is a SEM photo of the surface-plated copper-iron-nickel alloy foil prepared in Comparative Example 2 of the present invention; Fig.11 This is a SEM photo of the surface-plated copper-iron-nickel alloy foil prepared in Comparative Example 3 of the present invention; Fig.12 This is a SEM photo of the surface-plated copper-iron-nickel alloy foil prepared in Comparative Example 4 of the present invention; Fig.13 This is a SEM photograph of the surface-plated copper-iron-nickel alloy foil prepared in Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The preparation method of the surface-plated copper-iron-nickel alloy foil of the present invention is as follows: Step 1, separately arranging an anode plate and a cathode roller in an electrolytic cell, wherein the material of the anode plate is iridium titanium oxide, and the material of the cathode roller is titanium, adding an electrolyte into the electrolytic cell, applying a first current into the electrolyte, and depositing an iron-nickel alloy on the surface of the cathode roller to obtain an iron-nickel alloy foil; The electrolyte includes an iron solution, a nickel solution and a first additive; the electrolyte temperature is 45-65°C, and the first current density is 12-36A / dm 2 , electrolyte flow rate is 18~45m 3 / hr, the electrolyte pH is 2.0~3.0, and the solution pH is controlled by sodium bisulfate and sodium carbonate; The iron solution is ferrous sulfate, and the concentration of the iron solution is 30~120g / L; The nickel solution is nickel sulfate, and the concentration of the nickel solution is 10-55 g / L; The first additive includes an Fe reducing agent, a pH stabilizer, a conductive additive, a stress relaxant and a lubricant; Wherein, the Fe reducing agent is any one of ascorbic acid, glucose, glycine or sodium gluconate, and the addition amount is 0.5~4.5g / L; the Fe reducing agent can inhibit the oxidation precipitation of iron ions when used in an appropriate amount, but when the addition amount is less than 0.5g / L, it is difficult to achieve the effect of inhibiting the precipitation of iron ions. When the addition amount reaches 4.5g / L, the effect of inhibiting the precipitation of iron ions reaches the best. When the addition amount is greater than 4.5g / L, the effect will not be enhanced, but only plays a maintaining role, resulting in wasteful use of the additive.

[0019] The pH stabilizer is any one of glycine, sodium borate, boric acid, boron nitride or acetic acid, and the added amount is 10.0~35.0g / L; when the pH stabilizer is used in an appropriate amount, the pH value range of the electrolyte can be controlled, but when the added amount is less than 10.0g / L or exceeds 35.0g / L, the pH value will be biased to one side, and it is difficult to achieve the effect of maintaining pH stability.

[0020] The conductive aid is any one of sodium sulfate, sodium carbonate or sodium chloride, and the added amount is 7.5~27.5g / L; the conductive aid plays a role in assisting current conduction when used in an appropriate amount, but when the added amount is lower than 7.5g / L, it is difficult to achieve the above effect, and when the added amount exceeds 27.5g / L, stains and other quality deterioration problems will appear on the surface of the alloy foil.

[0021] The stress relaxer is any one of sodium allyl sulfonate, 2-propyl heptanol, sodium saccharin or bisbenzenesulfonimide, and the addition amount is 0.7~4.0g / L. When the stress relaxer is used in an appropriate amount, it can make the grains finer, reduce the internal stress, and play a role in reducing the surface roughness of the alloy foil and improving the tensile strength of the alloy foil. When the addition amount is less than 0.7g / L, it is difficult to achieve the above effect. When the addition amount is greater than 4.0g / L, the current efficiency is reduced, and it is difficult to achieve further effects at a certain point in time.

[0022] The lubricant is any one of sodium dodecylbenzene sulfonate, sodium hydroxyethyl sulfonate or sodium succinate, and the addition amount is 0.2~2.0g / L. When the lubricant is used in an appropriate amount, it can prevent surface defects such as pinholes, make the grains fine, and play a role in reducing the surface roughness of the alloy foil and improving the tensile strength of the alloy foil. When the addition amount is less than 0.2g / L, it is difficult to achieve the above effect. When the addition amount is greater than 2.0g / L, the tensile strength of the alloy foil will decrease and the surface will become rough.

[0023] like Figure 1 As shown, the preparation method of the electrolyte is as follows: adding the iron solution and ultrapure water to the 1# dissolution tank at the same time and stirring to dissolve, adding the nickel solution and ultrapure water to the 1# dirty liquid tank at the same time and stirring to dissolve, then mixing the two solutions evenly, filtering through a diatomaceous earth filter and adding them to the 1# clean liquid tank, stirring and dissolving the Fe reducing agent, pH stabilizer, conductive additive, stress reliever and lubricant with ultrapure water respectively, adding the solutions of the Fe reducing agent, pH stabilizer, conductive additive, stress reliever and lubricant to the 1# clean liquid tank, mixing and stirring evenly, and finally filtering through a fine filter to obtain the electrolyte for use.

[0024] Step 2, moving the iron-nickel alloy foil into a copper plating tank containing a copper plating solution through a roll-to-roll process, applying a second current to the copper plating solution to perform surface copper plating to obtain a copper-plated iron-nickel alloy foil; Wherein, the copper plating solution includes a copper sulfate solution and a second additive; The copper sulfate solution is prepared by mixing copper and sulfuric acid. The copper ion concentration in the copper plating solution is 40~55g / L, the sulfate ion concentration is 90~115g / L, and the hydrogen ion concentration is 1.15~1.30mol / L. In the electrolytic copper foil process of this application, sulfate ions (SO4 2- ) is higher than the copper ion (Cu 2+ ), this practice has nothing to do with the simple chemical bonding ratio, but is to ensure the stability and efficiency of the electrochemical electrolysis process. After sulfuric acid is highly ionized in the electrolyte, it can provide H + and SO4 2- ions, thereby improving the conductivity of the electrolyte and enhancing the current transmission efficiency, especially H + The ions have extremely high mobility, which can increase the sulfate ion to significantly improve the energy efficiency and electrolyte volume of the entire system.

[0025] The copper plating solution temperature is 40~45℃, and the second current density is 1~3A / dm 2 , copper plating liquid flow rate is 3~7 m 3 / hr; The second additive includes a flattening agent, a speed reducer, a polishing agent, a surfactant and a uniform electrodeposition aid; The flattening agent is any one of sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, 2-mercaptobenzothiazole or 2-mercapto-5-benzimidazolesulfonic acid sodium salt, and the addition amount is 3.0~15.0mg / L; when the flattening agent is used in an appropriate amount, it will inhibit the appearance of large protrusions in the metal structure and make it flat. When the addition amount is less than 3.0mg / L, it is difficult to achieve the flattening effect of the metal structure. When the addition amount is higher than 15.0mg / L, the surface roughness will increase excessively, causing problems such as pinholes on the surface.

[0026] The moderator is any one of polyethylene glycol, nonylphenol polyethylene glycol, carboxymethyl cellulose or hydroxypropyl cellulose, and the addition amount is 7.0~20.0mg / L; when the moderator is used in an appropriate amount, it can reduce the electrodeposition rate and prevent the surface roughness of the iron-nickel alloy foil from increasing sharply. However, when the addition amount is less than 7.0mg / L, the surface roughness of the iron-nickel alloy foil can increase rapidly, and when it exceeds 20.0mg / L, the effect will not be enhanced, which will cause a waste of raw materials.

[0027] The polishing agent is any one of 3-mercapto-1-propanesulfonic acid, sodium salt of o-ethylthiocarbonate-S-(3-sulfopropyl) ester or sodium salt of 3-(N,N-dimethylthiocarbamoyl)-thiopropanesulfonic acid, and the addition amount is 5.0~40.0mg / L; the polishing agent can increase the electrodeposition rate and enhance the surface gloss of the iron-nickel alloy foil when used in an appropriate amount. When the addition amount is less than 5.0mg / L, the surface gloss of the iron-nickel alloy foil may decrease, and when the addition amount is greater than 40.0mg / L, the surface roughness of the iron-nickel alloy foil increases, and spots will appear on the surface of the iron-nickel alloy foil.

[0028] The surfactant is sodium alkylbenzene sulfonate, and the addition amount is 0.2~3.0g / L; the surfactant plays a role in maximizing the interfacial bonding between the copper plating layer and the iron-nickel alloy foil, and at the same time, by adjusting the surface tension during the electroplating process, the copper layer can be evenly diffused. The surfactant used to improve the interfacial bonding can increase the affinity between the copper plating layer and the iron-nickel alloy foil and promote the diffusion of atoms inside the plating layer, thereby helping to form a stronger interfacial bond. In this way, the surfactant can protect the plating layer from being easily peeled off due to external impact or thermal changes. In particular, when the surfactant is added within the appropriate concentration range (0.2~3.0g / L), the uniformity and adhesion of the plating layer can be ensured, and the copper layer can be stably formed on the surface of the iron-nickel alloy foil. However, if the addition amount is less than 0.2g / L, the interfacial bonding may not be fully formed, resulting in an increased risk of copper layer peeling; and if the addition amount exceeds 3.0g / L, unnecessary foam may form in the plating solution, thereby reducing the quality of the plating layer. Therefore, it is crucial to maintain an appropriate concentration. In this way, the interfacial bonding strength between the copper layer and the iron-nickel alloy foil can be maximized and long-term durability can be ensured.

[0029] The uniform electrodeposition aid is chromium chloride, and the addition amount is 3.0~30mg / L. The role of the uniform electrodeposition aid is to promote the formation of a uniform coating, thereby assisting the surfactant to improve the interfacial bonding force. That is, the uniform electrodeposition aid helps the copper layer to be formed more uniformly on the surface of the iron-nickel alloy foil by improving the micro-uniformity of the coating. In this way, the local stress concentration at the interface can be minimized, and the uniformity of the entire coating can be ensured, thereby improving long-term durability. In addition, when a uniform coating is formed, the metal atoms at the interface diffuse more smoothly, thereby maximizing the effect of the surfactant and ultimately helping to form a higher interfacial bonding force. However, if the addition amount of the uniform electrodeposition aid is less than 3.0mg / L, it is difficult to form a uniform coating; if the addition amount of the uniform electrodeposition aid exceeds 30.0mg / L, it may cause the coating to be too thick or the uniformity to decrease, so it is crucial to maintain an appropriate concentration.

[0030] like Figure 2As shown, the preparation method of the copper plating solution is as follows: copper and sulfuric acid are added to a 2# dissolving tank at the same time, stirred and dissolved, and then the copper concentration is adjusted through a 2# dirty liquid tank, and the solution is added to a 2# clean liquid tank after filtering through a diatomaceous earth filter; a flattening agent, a speed reducer, a polishing agent, a surfactant and a uniform electrodeposition aid are stirred and dissolved respectively with ultrapure water, and the solutions of the flattening agent, the speed reducer, the polishing agent, the surfactant and the uniform electrodeposition aid are added to the 2# clean liquid tank, mixed and stirred evenly, and finally filtered through a fine filter to obtain a copper plating solution for use.

[0031] Step 3: Move the copper-plated iron-nickel alloy foil to a chromium anti-oxidation tank containing Cr anti-rust liquid through a roll-to-roll process for Cr anti-rust treatment, and roll it up to obtain the copper-plated iron-nickel alloy foil.

[0032] The Cr anti-rust solution includes chromium trioxide and glucose, the addition amount of chromium trioxide is 1.1 kg / L, and the addition amount of glucose is 7.0 kg / L; The temperature of Cr anti-rust liquid is 20~22℃, and the flow rate of Cr anti-rust liquid is 2~6 m 3 / hr, pH value of Cr rust preventive liquid is less than or equal to 3.5. like Figure 3 As shown, the preparation method of Cr anti-rust liquid is as follows: put chromium trioxide and glucose into a Cr dissolution tank together, then add ultrapure water to dissolve and stir, filter through a fine filter, and then add it into the chromium anti-oxidation tank for use.

[0033] Chromium trioxide (CrO3) is a substance containing hexavalent chromium (Cr 6+ ) is a representative compound with strong oxidizing property. In the present invention, in order to reduce the toxicity and environmental impact of chromium trioxide, a reducing agent, glucose, is added to reduce Cr 6+ Reduction to Cr 3+ This reduction treatment regulates Cr 6+ The reactivity of Cr induces the formation of a more stable trivalent chromium-based chromium oxide film (such as CrO3 or Cr(OH)3, etc.) on the metal surface, thereby reducing the environmental impact while maintaining the anti-rust effect. 6+ Reduced to Cr 3+ When the toxicity is greatly reduced, the chemical stability in aqueous solution is improved, and the film formed on the metal surface acts as a uniform and highly adhesive protective layer. 3+ In the electrically neutral state, the reactivity with the copper foil surface is stable, and it can only play the rust prevention function without causing excessive oxidation or surface damage.

[0034] The copper-plated iron-nickel alloy foil is prepared by the preparation method of the present invention. The copper-plated iron-nickel alloy foil has a thickness of 8 μm, a surface roughness of Ra: 0.25-0.35 μm, a surface roughness of Rz: 1.15-1.30 μm, a tensile strength of 1320 MPa-1500 MPa at room temperature, and an elongation of 2.30%-3.70% at room temperature. After heat treatment at 180°C for 1 hour, the tensile strength of the copper-plated iron-nickel alloy foil is 1230 MPa-1380 MPa, the elongation is 3.3%-4.7%, and the conductivity is 3.0×10 7 S / m and above.

[0035] The surface copper-plated iron-nickel alloy foil prepared by the invention can be applied to the fields of printed circuit boards, high-performance electronic equipment, high-frequency communication equipment, etc.

[0036] The copper-plated iron-nickel alloy foil prepared by the present invention combines the advantages of traditional copper foil and iron-nickel alloy foil, has excellent tensile strength and high elongation, and still has relatively stable tensile strength and elongation after high-temperature heat treatment at 180°C. In addition, due to its high conductivity, it can be used as a high-performance material in industries and application fields that are not involved due to the limitations of traditional materials. Among them, when used in fields such as printed circuit boards, high-performance electronic devices and high-frequency communication equipment, ultra-high-speed signal transmission can be achieved without reducing performance, and stable performance can be maintained for a long time. In addition, the copper-plated iron-nickel alloy foil of the present invention is not limited to specific industries, but can also be used as the core material of high-performance products in a variety of industrial fields, and become an important part of innovative solutions.

[0037] The present invention solves the peeling problem that may occur in the prior art by applying a process that maximizes the interfacial bonding force between the copper layer and the iron-nickel alloy foil. Since the bonding force between the copper-plated layer and the iron-nickel alloy foil is easily separated due to external impact, high temperature environment or repeated stress, in order to prevent this phenomenon, a surfactant is added at an optimal concentration in the electroplating process to enhance the interfacial bonding force. The surfactant can increase the interfacial affinity between the copper foil layer and the iron-nickel alloy foil and promote the diffusion of metal atoms, thereby forming a stronger bonding structure. In this way, the copper plating layer can be uniformly deposited and the occurrence of micropores or peeling phenomena can be prevented. In addition, when the surfactant is added at an optimal concentration, the stress concentration phenomenon caused by the difference in thermal expansion coefficient can be alleviated, thereby maintaining high reliability in long-term use. By applying this interfacial bonding force enhancement technology, the copper-plated iron-nickel alloy foil of the present invention has higher durability and reliability than traditional copper foil and ordinary iron-nickel alloy foil.

[0038] In printed circuit boards and high-frequency communication devices where high-speed signal transmission is crucial, it is able to maintain stable performance for a long time and also exhibit excellent performance under repeated thermal changes and mechanical stress environments. The copper-plated iron-nickel alloy foil developed by the present invention not only has high conductivity, excellent mechanical strength and outstanding heat resistance, but also by maximizing interfacial bonding strength, it is expected to play a core role in a variety of industries that require high-performance materials.

[0039] The preparation method of the surface-plated copper-iron-nickel alloy foil of the present invention is specifically as follows: (1) Ferrous sulfate is added to the No. 1 dissolution tank through the No. 1 quantitative supply device, and ultrapure water is supplied for dissolution and stirring; nickel sulfate is added to the No. 1 waste liquid tank through the No. 2 quantitative supply device, and ultrapure water is supplied for dissolution and stirring; (2) preparing an electrolyte solution by circulating and fusing the above two solutions, wherein the electrolyte temperature is controlled by a heat exchanger; (3) Check the pH value of the electrolyte and keep it within the appropriate range using sulfuric acid and sodium carbonate; (4) removing impurities from the electrolyte through a diatomaceous earth filter and moving it to No. 1 clean liquid tank; (5) Add Fe reducing agent and ultrapure water to the additive A tank, dissolve and stir; add pH stabilizer and ultrapure water to the additive B tank, dissolve and stir; add conductive additive and ultrapure water to the additive C tank, dissolve and stir; add stress relaxant and ultrapure water to the additive D tank, dissolve and stir; add lubricant and ultrapure water to the additive E tank, dissolve and stir; transfer the dissolved 5 additive solutions into the 1# clean liquid tank; (6) The electrolyte containing additives is filtered through a fine filter, and after the electrolyte temperature is controlled by a heat exchanger, it is supplied to the electrolytic cell of the alloy foil production machine (the electrolyte overflowing from the electrolytic cell is moved to the waste liquid tank again); (7) copper and sulfuric acid are put into the 2# dissolving tank, and then dissolved and stirred to obtain a copper sulfate solution; the dissolved copper sulfate solution is circulated through the 2# waste liquid tank to adjust the copper concentration, and at this time, the solution temperature is controlled by a heat exchanger; (8) Remove impurities through a diatomaceous earth filter and transfer to the No. 2 clean liquid tank; (9) Add a flattening agent and ultrapure water to the additive F tank, dissolve and stir; add a speed reducer and ultrapure water to the additive G tank, dissolve and stir; add a polishing agent and ultrapure water to the additive H tank, dissolve and stir; add a surfactant and ultrapure water to the additive I tank, dissolve and stir; add a uniform electrodeposition aid and ultrapure water to the additive J tank, dissolve and stir; transfer the dissolved 5 additive solutions to the 2# clean liquid tank; (10) The plating solution containing the five additives is filtered through a fine filter, the temperature of the plating solution is controlled by a heat exchanger, and then supplied to the copper plating tank of the raw foil machine; (11) Chromium trioxide and glucose are placed together in a Cr dissolution tank, and then ultrapure water is supplied to dissolve and stir, and the dissolved rust-proof liquid is transferred to the Cr supply tank; (12) The anti-rust liquid transferred to the Cr supply tank is filtered through a fine filter, and after the temperature of the anti-rust liquid is controlled by a heat exchanger, it is transferred to the chromium anti-oxidation tank of the foil production machine; (13) supplying electric current to a cathode roller and an anode plate in an electrolytic cell to electrodeposit on the cathode roller to produce an iron-nickel alloy foil; (14) The manufactured iron-nickel alloy foil is moved through a roll-to-roll process and passes through a copper plating tank that supplies current to be copper-plated on the surface; (15) The copper-plated iron-nickel alloy foil is subjected to a roll-to-roll process and then to a chromium anti-oxidation tank for Cr anti-rust treatment; (16) After the final Cr anti-rust treatment in the roll-to-roll process, the surface of the roll is plated with copper-iron-nickel alloy foil; (17) After heat treatment in an oven at 180°C for 1 hour, the final manufacturing is completed.

[0040] By using the preparation method of the present invention, a surface-plated copper-iron-nickel alloy foil with a thickness of 6 to 10 μm can also be prepared.

[0041] Example 1 The preparation method of the copper-iron-nickel alloy foil plated on the surface of this embodiment is as follows: In the electrolyte solution in the electrolytic cell, current is applied to the cathode roller and anode plate spaced apart from each other, and the iron-nickel alloy foil is electrodeposited on the surface of the cathode roller, and the surface copper plating process and electroless Cr anti-rust treatment process are carried out through a roll-to-roll manufacturing process and rolled up, and the final manufacturing is completed after heat treatment at 180°C in an oven for 1 hour. The iron ions and nickel ions are extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content is 39.8g / L, the nickel sulfate content is 15.5g / L, the electrolyte temperature is 45°C, and the current density is 14.1A / dm 2 , the electrolyte flow rate is 18 m 3 / hr, and the pH value was maintained at 2.5±0.5 using sodium bisulfate and sodium carbonate. Finally, the additives added to the iron-nickel alloy foil electrolyte were dissolved by ultrapure water and stirred in each tank. The contents of the electrolyte additives were as follows: Ascorbic acid was used as the Fe reducing agent (additive A) at a dosage of 0.5 g / L; The pH stabilizer (additive B) uses boron nitride, and the addition amount is 10.0g / L; The conductivity aid (additive C) is sodium sulfate, and the addition amount is 7.5g / L; The stress reliever (additive D) was sodium saccharin, with an addition amount of 0.7 g / L; The lubricant (additive E) is sodium dodecylbenzene sulfonate, and the addition amount is 0.2 g / L.

[0042] In addition, the bath parameters for surface copper plating are copper ion concentration 45.0 g / L, sulfate ion concentration 105.0 g / L, bath temperature 42.0 ± 0.5 °C, current density 2 A / dm 2 , flow rate is 5.0m 3 / hr. The additives added to the plating solution are dissolved in ultrapure water and stirred in each tank. The content of the additives in the above plating solution is as follows: The flattening agent (additive F) is sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, and the addition amount is 3.0 mg / L; The speed reducer (additive G) uses nonylphenol polyethylene glycol, and the addition amount is 7.0 mg / L; The polishing agent (additive H) uses 3-mercapto-1-propanesulfonic acid, and the addition amount is 5.0 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 0.2 g / L; The uniform plating agent (additive J) uses chromium chloride with an addition amount of 3.0 mg / L.

[0043] Then, the anti-rust liquid for Cr anti-rust treatment was prepared by adding glucose as a reducing agent to chromium trioxide, dissolving and stirring with ultrapure water, with the addition amount of chromium trioxide being 1.1 kg / L and the addition amount of glucose being 7.0 kg / L; the temperature of the anti-rust liquid was 21.0±1.0℃, and the flow rate was 4.5m 3 / hr, pH value is ≤3.5. By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0044] Example 2 The preparation method of the copper-iron-nickel alloy foil on the surface of this embodiment is the same as that of Embodiment 1, and the differences from Embodiment 1 are as follows: The iron ions and nickel ions in the electrolyte solution were extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content was 60.3 g / L, the nickel sulfate content was 22.6 g / L, the electrolyte temperature was 50 °C, and the current density was 19.6 A / dm 2 , electrolyte flow rate is 25m 3 / hr, and the pH was maintained at 2.5 ± 0.5 using sodium bisulfate and sodium carbonate.

[0045] The content of additives added to the iron-nickel alloy foil electrolyte is as follows: The Fe reducing agent (additive A) was glycine, with an addition amount of 1.5 g / L; The pH stabilizer (additive B) uses boric acid, and the addition amount is 16.3 g / L; The conductivity aid (additive C) is sodium sulfate, and the addition amount is 12.5g / L; The stress reliever (additive D) is saccharin sodium, and the addition amount is 1.4 g / L; The lubricant (additive E) uses sodium dodecylbenzene sulfonate, and the addition amount is 0.6 g / L; In addition, the bath parameters for surface copper plating are 40.0 g / L copper ions, 90.0 g / L sulfuric acid, a solution temperature of 44.5 ± 0.5 °C, and a current density of 1 A / dm 2 , flow rate is 3m 3 / hr.

[0046] The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) uses 2-mercaptobenzothiazole, and the addition amount is 6.0 mg / L; The speed reducer (additive G) uses nonylphenol polyethylene glycol, and the addition amount is 10.2 mg / L; The polishing agent (additive H) uses 3-mercapto-1-propanesulfonic acid, and the addition amount is 13.7 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 0.9 g / L; The uniform plating agent (additive J) uses chromium chloride, and the addition amount is 9.8 mg / L.

[0047] Cr anti-rust liquid flow rate is 2m 3 / hr. By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0048] Example 3 The preparation method of the copper-iron-nickel alloy foil on the surface of this embodiment is the same as that of Embodiment 1, and the differences from Embodiment 1 are as follows: The iron ions and nickel ions in the electrolyte solution were extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content was 73.5 g / L, the nickel sulfate content was 30.1 g / L, the electrolyte temperature was 55 °C, and the current density was 27.4 A / dm 2 , electrolyte flow rate is 35m 3 / hr, and the pH was maintained at 2.5 ± 0.5 using sodium bisulfate and sodium carbonate.

[0049] The content of additives added to the iron-nickel alloy foil electrolyte is as follows: Glucose was used as Fe reducing agent (additive A) at an addition amount of 2.5 g / L; The pH stabilizer (additive B) uses sodium borate, and the addition amount is 22.6g / L; The conductivity aid (additive C) is sodium carbonate, and the addition amount is 17.5g / L; The stress relaxant (additive D) is bis-benzenesulfonimide, and the addition amount is 2.2 g / L; The lubricant (additive E) uses sodium dodecylbenzene sulfonate, and the addition amount is 1.1 g / L; In addition, the bath parameters for surface copper plating are copper ion concentration 55.0 g / L, sulfate ion concentration 115.0 g / L, solution temperature 40.5 ± 0.5 °C, current density 3 A / dm 2 , flow rate is 7.0m 3 / hr.

[0050] The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) is sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, and the addition amount is 9.0 mg / L; The speed reducer (additive G) uses polyethylene glycol propylene glycol ether, and the addition amount is 13.5 mg / L; The polishing agent (additive H) uses sodium salt of o-ethylthiocarbonate-S-(3-sulfopropyl) ester, and the addition amount is 22.4 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 1.6 g / L; The uniform plating agent (additive J) uses chromium chloride with an addition amount of 16.5 mg / L.

[0051] Cr anti-rust liquid flow rate is 6m 3 / hr. By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0052] Example 4 The preparation method of the copper-iron-nickel alloy foil on the surface of this embodiment is the same as that of Embodiment 1, and the differences from Embodiment 1 are as follows: The iron ions and nickel ions in the electrolyte solution were extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content was 71.4 g / L and the nickel sulfate content was 38.9 g / L. The electrolyte temperature was 60 °C and the current density was 31.5 A / dm 2 , the electrolyte flow rate is 40 m 3 / hr, and the pH was maintained at 2.5 ± 0.5 using sodium bisulfate and sodium carbonate.

[0053] The content of additives added to the iron-nickel alloy foil electrolyte is as follows: The Fe reducing agent (additive A) was sodium gluconate, with an addition amount of 3.5 g / L; The pH stabilizer (additive B) uses acetic acid, and the addition amount is 28.8g / L; The conductivity aid (additive C) is sodium chloride, and the addition amount is 22.5g / L; The stress relaxant (additive D) is 2-propylheptanol, and the addition amount is 3.1 g / L; The lubricant (additive E) uses sodium hydroxyethyl sulfonate, and the addition amount is 1.6 g / L; The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) uses 2-mercaptobenzothiazole, and the addition amount is 12.0 mg / L; The speed reducer (additive G) is carboxymethyl cellulose, and the addition amount is 16.7 mg / L; The polishing agent (additive H) uses sodium 3-(N,N-dimethylthiocarbamoyl)-thiopropane sulfonate, and the addition amount is 31.2 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 2.3 g / L; The uniform plating agent (additive J) uses chromium chloride, and the addition amount is 23.3 mg / L.

[0054] By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0055] Example 5 The preparation method of the copper-iron-nickel alloy foil on the surface of this embodiment is the same as that of Embodiment 1, and the differences from Embodiment 1 are as follows: The iron ions and nickel ions in the electrolyte solution were extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content was 120 g / L, the nickel sulfate content was 55 g / L, the electrolyte temperature was 65 °C, and the current density was 36 A / dm 2 , electrolyte flow rate is 45m 3 / hr, and the pH was maintained at 2.5 ± 0.5 using sodium bisulfate and sodium carbonate.

[0056] The content of additives added to the iron-nickel alloy foil electrolyte is as follows: Ascorbic acid was used as the Fe reducing agent (additive A) at a dosage of 4.5 g / L; The pH stabilizer (additive B) uses glycine, and the addition amount is 35.0 g / L; The conductivity aid (additive C) is sodium chloride, and the addition amount is 27.5g / L; The stress relaxant (additive D) is sodium allyl sulfonate, and the addition amount is 4.0 g / L; The lubricant (additive E) uses sodium succinate, and the addition amount is 2.0g / L; The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) is sodium 2-mercapto-5-benzimidazole sulfonate, and the addition amount is 15.0 mg / L; The speed reducer (additive G) uses hydroxypropyl cellulose, and the addition amount is 20.0 mg / L; The polishing agent (additive H) uses sodium 3-(N,N-dimethylthiocarbamoyl)-thiopropane sulfonate, and the addition amount is 40.0 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 3.0 g / L; The uniform plating agent (additive J) uses chromium chloride, and the addition amount is 30.0 mg / L.

[0057] By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0058] Example 6 The preparation method of the copper-iron-nickel alloy foil on the surface of this embodiment is the same as that of Embodiment 1, and the differences from Embodiment 1 are as follows: The iron ions and nickel ions in the electrolyte solution were extracted by ferrous sulfate and nickel sulfate, respectively. The ferrous sulfate content was 30 g / L, the nickel sulfate content was 10 g / L, the electrolyte temperature was 50 °C, and the current density was 12 A / dm 2 , electrolyte flow rate is 35m 3 / hr, and the pH was maintained at 2.5 ± 0.5 using sodium bisulfate and sodium carbonate.

[0059] The content of additives added to the iron-nickel alloy foil electrolyte is as follows: Ascorbic acid was used as the Fe reducing agent (additive A) at a dosage of 4.5 g / L; The pH stabilizer (additive B) uses acetic acid, and the addition amount is 28.6 g / L; The conductivity aid (additive C) is sodium chloride, and the addition amount is 27.5g / L; The stress relaxant (additive D) is sodium allyl sulfonate, and the addition amount is 4.0 g / L; The lubricant (additive E) uses sodium succinate, and the addition amount is 2.0g / L; The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) uses 2-mercaptobenzothiazole, and the addition amount is 6.0 mg / L; The speed reducer (additive G) uses nonylphenol polyethylene glycol, and the addition amount is 10.2 mg / L; The polishing agent (additive H) uses 3-mercapto-1-propanesulfonic acid, and the addition amount is 13.7 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 0.9 g / L; The uniform plating agent (additive J) uses chromium chloride, and the addition amount is 9.8 mg / L.

[0060] By using the above-mentioned manufacturing method and additives, an iron-nickel alloy foil having a surface copper plating and a thickness of 8 μm was manufactured.

[0061] Comparative Example 1 The preparation method of the surface-plated copper-iron-nickel alloy foil in this comparative example is the same as that in Example 1, and the differences from Example 1 are as follows: The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) is sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, and the addition amount is 3.0 mg / L; The speed reducer (additive G) uses nonylphenol polyethylene glycol, and the addition amount is 7.0 mg / L; The polishing agent (additive H) uses 3-mercapto-1-propanesulfonic acid, and the addition amount is 5.0 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 0.1 g / L; The uniform plating agent (additive J) uses chromium chloride with an addition amount of 1.5 mg / L.

[0062] Comparative Example 2 The preparation method of the surface-plated copper-iron-nickel alloy foil of this comparative example is the same as that of Example 2, and the differences from Example 2 are as follows: No surfactant or uniform electrodeposition aid is added to the copper plating solution.

[0063] Comparative Example 3 The preparation method of the surface-plated copper-iron-nickel alloy foil in this comparative example is the same as that in Example 3, and the difference from Example 3 is as follows: No surfactant is added to the copper plating solution.

[0064] Comparative Example 4 The preparation method of the surface-plated copper-iron-nickel alloy foil of this comparative example is the same as that of Example 4, and the differences from Example 4 are as follows: No uniform plating agent is added to the copper plating solution.

[0065] Comparative Example 5 The preparation method of the surface-plated copper-iron-nickel alloy foil of this comparative example is the same as that of Example 5, and the differences from Example 5 are as follows: The content of additives added to the copper plating solution is as follows: The flattening agent (additive F) is sodium 2-mercapto-5-benzimidazole sulfonate, and the addition amount is 15.0 mg / L; The speed reducer (additive G) uses hydroxypropyl cellulose, and the addition amount is 20.0 mg / L; The polishing agent (additive H) uses sodium 3-(N,N-dimethylthiocarbamoyl)-thiopropane sulfonate, and the addition amount is 40.0 mg / L; The surfactant (additive I) is sodium alkylbenzene sulfonate, and the addition amount is 5.0 g / L; The uniform plating agent (additive J) uses chromium chloride, and the addition amount is 40.0 mg / L; Comparative Example 6 The preparation method of the surface-plated copper-iron-nickel alloy foil of this comparative example is the same as that of Example 6, and the differences from Example 6 are as follows: No surfactant or uniform electrodeposition aid is added to the copper plating solution.

[0066] The dosage of additives in Examples 1 to 6 and Comparative Examples 1 to 6 is shown in Tables 1 and 2: Table 1 The dosage of the first additive in Examples 1 to 6 and Comparative Examples 1 to 6

[0067] Table 2 The dosage of the second additive in Examples 1 to 6 and Comparative Examples 1 to 6

[0068] The copper-iron-nickel alloy foils prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were respectively subjected to performance tests, and the test items included thickness, surface roughness (Ra) of the S surface, surface roughness (Rz) of the M surface, tensile strength at room temperature, elongation at room temperature, current conductivity and appearance, as shown in Table 3.

[0069] Table 3 Performance of the copper-plated iron-nickel alloy foil prepared in Examples 1 to 6 and Comparative Examples 1 to 6

[0070] The copper-plated iron-nickel alloy foils prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were heat treated at 180° C. for 1 h, and then cooled to room temperature to measure their tensile strength and elongation. The results are shown in Table 4.

[0071] Table 4 Performance of copper-plated iron-nickel alloy foils prepared in Examples 1 to 6 and Comparative Examples 1 to 6 after treatment at 180°C

[0072] It can be seen from Tables 3 and 4 that the copper-plated iron-nickel alloy foil prepared by the method of the present invention still has good tensile strength and elongation after high-temperature treatment, has high tensile strength and high elongation unique to iron-nickel alloy foil, and still has relatively stable tensile strength and elongation after high-temperature heat treatment at 180°C, and has excellent current conductivity.

[0073] The core goal of the copper-iron-nickel alloy foil produced by the present invention is to maximize the interfacial bonding and improve the physical properties by optimizing the additive composition. In order to evaluate this, the influence of the additive composition on the interfacial bonding, physical properties, coating uniformity and mechanical properties was analyzed.

[0074] In the embodiment, when copper is plated on an iron-nickel alloy foil, an optimal combination of surfactant and uniform electrodeposition aid is applied. Figures 4 to 8 As shown, a uniform coating is formed, high interface bonding strength and excellent mechanical properties are obtained. On the contrary, in the comparative example, due to improper application of additive composition, the interface bonding strength is reduced, the coating uniformity is deteriorated and various problems are caused.

[0075] In Comparative Example 1, due to the insufficient concentration of surfactant and uniform electrodeposition aid, the interfacial bonding force of the coating is low and the surface roughness increases. The surface roughness of S is 0.42 μm, and the surface roughness of M is 1.38 μm. Fig. 9 As shown in the figure, the roughness is higher than that of the embodiment, the coating is unevenly formed, the tensile strength at room temperature is reduced to 1257 MPa (lower than that of embodiment 1), and the conductivity is as low as 2.5×10 7 S / m, surface peeling and cracking were observed in the appearance evaluation. This indicates that the adhesion between the coating and the substrate is weakened due to insufficient interface bonding.

[0076] In comparative example 2, electroplating was performed without adding any surfactant or uniform electrodeposition aid. As a result, the interfacial bonding strength of the coating decreased significantly and the surface roughness increased. The surface roughness of S was 0.65 μm, and the surface roughness of M was 1.79 μm. Fig.10 As shown, it is the highest value in the comparative example, indicating that the coating is not uniformly formed and there are many local protrusions. The tensile strength at room temperature is the lowest (996MPa), and the elongation is reduced to 2.03% (significantly lower than that of Example 2). The conductivity drops sharply to 1.3×10 7 S / m, which was analyzed as an incomplete conductive path due to micropores inside the coating and uneven coating. Delamination was observed in the appearance inspection, accompanied by surface warping and local cracks. This confirms that surfactants and uniform electrodeposition additives play a key role in ensuring interface bonding and coating uniformity.

[0077] In Comparative Example 3, although a uniform electrodeposition aid is included, no surfactant is added, resulting in insufficient interface bonding between the copper plating layer and the iron-nickel alloy foil. The surface roughness of S is 0.55 μm, and the surface roughness of M is 1.71 μm. Fig.11 As shown, there are local areas with weak bonding. The room temperature tensile strength and elongation are lower than those in Example 3. The conductivity is reduced to 1.7×10 7S / m, indicating that the diffusion of atoms at the interface is hindered. Local peeling was found in the appearance inspection, proving that the surfactant plays a core role in promoting uniform diffusion and improving interface affinity.

[0078] In comparative example 4, the lack of uniform electrodeposition additives leads to a decrease in the uniformity of the coating. The surface roughness of S is 0.56 μm, and the surface roughness of M is 1.73 μm. Fig.12 As shown in the figure, the coating is unevenly formed. The room temperature tensile strength (1062MPa) and room temperature elongation (1.99%) are both reduced. The electrical conductivity (2.3×10 7 The decrease in S / m) indicated localized conductivity degradation due to uneven plating. Visual inspection confirmed the uneven plating.

[0079] In comparative example 5, excessive addition of surfactant and uniform electrodeposition aid resulted in excess stress and internal defects in the coating. The surface roughness of S reached 0.51 μm, and the surface roughness of M reached 1.63 μm. Fig.13 As shown, the overgrowth leads to a rough surface. Although the conductivity (2.6×10 7 S / m) is relatively high, but the tensile strength (1121MPa) and elongation (1.80%) are the lowest among the comparative examples. Appearance inspection revealed coating cracks, confirming that excessive additives lead to coating embrittlement.

[0080] The situation of Comparative Example 6 is the same as that of Comparative Example 2, and will not be described again here.

[0081] The results of comprehensive analysis of comparative examples 1 to 6 show that the surfactant and the uniform electrodeposition additive play an indispensable role in maximizing the interfacial bonding force between the copper coating and the iron-nickel alloy foil and ensuring the uniformity of the coating. Insufficient surfactant leads to decreased interfacial bonding force, insufficient uniform electrodeposition additive affects uniformity, and excessive addition deteriorates the quality of the coating. This confirms that the manufacturing method of the present invention can optimize the interfacial bonding force while improving mechanical properties and conductivity.

[0082] As can be seen from Tables 1 to 3, the optimal combination of surfactant and uniform electrodeposition aid can maximize the interfacial bonding force, and the examples show excellent mechanical properties and electrical properties, while the comparative examples have surface defects due to insufficient bonding force and uneven coating.

Claims

1. A method for preparing a copper-iron-nickel alloy foil having a surface coating, characterized in that: The specific method is as follows: Step 1, separately arranging an anode plate and a cathode roller in an electrolytic cell, wherein the material of the anode plate is iridium titanium oxide, and the material of the cathode roller is titanium, adding an electrolyte into the electrolytic cell, applying a first current into the electrolyte, and depositing an iron-nickel alloy on the surface of the cathode roller to obtain an iron-nickel alloy foil; Step 2, moving the iron-nickel alloy foil into a copper plating tank containing a copper plating solution through a roll-to-roll process, applying a second current to the copper plating solution to perform surface copper plating to obtain a copper-plated iron-nickel alloy foil; Step 3: Move the copper-plated iron-nickel alloy foil to a chromium anti-oxidation tank containing Cr anti-rust liquid through a roll-to-roll process for Cr anti-rust treatment, and roll it up to obtain the copper-plated iron-nickel alloy foil.

2. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 1, characterized in that: The electrolyte includes an iron solution, a nickel solution and a first additive; the electrolyte temperature is 45-65°C, and the first current density is 12-36A / dm 2 , electrolyte flow rate is 18~45m 3 / hr, the electrolyte pH is 2.0~3.0, and the solution pH is controlled by sodium bisulfate and sodium carbonate.

3. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 2, characterized in that: The iron solution is ferrous sulfate, and the concentration of the iron solution is 30-120 g / L; the nickel solution is nickel sulfate, and the concentration of the nickel solution is 10-55 g / L; The first additive includes an Fe reducing agent, a pH stabilizer, a conductive additive, a stress relaxant and a lubricant; The Fe reducing agent is any one of ascorbic acid, glucose, glycine or sodium gluconate, and the addition amount is 0.5-4.5 g / L; The pH stabilizer is any one of glycine, sodium borate, boric acid, boron nitride or acetic acid, and the addition amount is 10.0-35.0 g / L; The conductive additive is any one of sodium sulfate, sodium carbonate or sodium chloride, and the addition amount is 7.5~27.5g / L; The stress relaxant is any one of sodium allyl sulfonate, 2-propyl heptanol, sodium saccharin or bisbenzenesulfonimide, and the added amount is 0.7-4.0 g / L; The lubricant is any one of sodium dodecylbenzene sulfonate, sodium hydroxyethyl sulfonate or sodium succinate, and the added amount is 0.2-2.0 g / L.

4. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 1, characterized in that: The copper plating solution includes a copper sulfate solution and a second additive; The copper sulfate solution is prepared by mixing copper and sulfuric acid, wherein the copper ion concentration in the copper plating solution is 40-55 g / L, the sulfate ion concentration is 90-115 g / L, and the hydrogen ion concentration is 1.15-1.30 mol / L; The copper plating solution temperature is 40-45°C, and the second current density is 1-3A / dm 2 , copper plating liquid flow rate is 3~7 m 3 / hr.

5. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 4, characterized in that: The second additive includes a flattening agent, a speed reducer, a polishing agent, a surfactant and a uniform electrodeposition aid; The flattening agent is any one of sodium 3-(5-mercapto-1-tetraacyl)benzenesulfonate, 2-mercaptobenzothiazole or 2-mercapto-5-benzimidazolesulfonic acid sodium salt, and the addition amount is 3.0-15.0 mg / L; The moderator is any one of polyethylene glycol, nonylphenol polyethylene glycol, carboxymethyl cellulose or hydroxypropyl cellulose, and the addition amount is 7.0-20.0 mg / L; The polishing agent is any one of 3-mercapto-1-propanesulfonic acid, o-ethylthiocarbonate-S-(3-sulfopropyl) ester sodium salt or 3-(N,N-dimethylthiocarbamoyl)-thiopropanesulfonic acid sodium salt, and the addition amount is 5.0-40.0 mg / L; The surfactant is sodium alkylbenzene sulfonate, and the addition amount is 0.2-3.0 g / L; The uniform electrodeposition aid is chromium chloride, and the addition amount is 3.0-30 mg / L.

6. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 1, characterized in that: The Cr anti-rust liquid includes chromium trioxide and glucose, the chromium trioxide addition amount is 1.1 kg / L, and the glucose addition amount is 7.0 kg / L.

7. The method for preparing the surface-plated copper-iron-nickel alloy foil according to claim 6, characterized in that: The temperature of the Cr anti-rust liquid is 20-22°C, and the flow rate of the Cr anti-rust liquid is 2-6 m 3 / hr, pH value of Cr rust preventive liquid is less than or equal to 3.

5.

8. Surface-plated copper-iron-nickel alloy foil, characterized in that: The copper-plated iron-nickel alloy foil is prepared by the preparation method of any one of claims 1 to 7, and the thickness of the copper-plated iron-nickel alloy foil is 8 μm, the surface roughness of S is Ra: 0.25-0.35 μm, the surface roughness of M is Rz: 1.15-1.30 μm, the tensile strength at room temperature is 1320 MPa-1500 MPa, the elongation at room temperature is 2.30%-3.70%, and the conductivity is 3.0×10 7 S / m and above.

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