A silver-gray electromagnetic shielding copper foil and a method for manufacturing the same

Abstract

The application provides a silver-gray electromagnetic shielding copper foil and a preparation method thereof. The silver-gray electromagnetic shielding copper foil comprises the following steps: providing a copper foil to be treated; sequentially performing surface oil removal and acid solution cleaning on the copper foil to be treated to obtain a treated copper foil; providing a blackening treatment solution; immersing the treated copper foil into the blackening treatment solution for blackening treatment to obtain a blackened copper foil; placing the blackened copper foil into a metal plating solution for surface electroplating treatment to electroplate a silver-gray magnetic shielding alloy layer on the surface of the blackened copper foil to obtain an electroplated copper foil; and performing anti-oxidation treatment on the electroplated copper foil to form a protective film on the surface of the electroplated copper foil to obtain the silver-gray electromagnetic shielding copper foil. The silver-gray electromagnetic shielding copper foil prepared by the application has a unique silver-gray appearance on one side or both sides, and has good intermodulation performance and shielding performance, thereby meeting the appearance requirements of an automatic assembly line optical recognition positioning system and the electromagnetic shielding performance requirements of an electronic device.

Description

Technical Field

[0001] This invention belongs to the technical field of metal surface treatment, specifically relating to a silver-gray electromagnetic shielding copper foil and its preparation method. Background Technology

[0002] With the rapid development of technology, electronic products such as 3C electronics and smart wearable devices are constantly being innovated. These electronic devices are increasingly developing towards miniaturization, integration, and high performance. In this process, the circuit density inside the devices is constantly increasing, and the electromagnetic interference problem between various electronic components is becoming more and more prominent. If the interference of ambient electromagnetic waves on the panel circuit cannot be effectively shielded, it will seriously affect the device. By using shielding materials to shield the panel circuit from the interference of ambient electromagnetic waves, the integrity of the circuit board signal transmission can be improved, and the performance, stability, and reliability of the device can be enhanced. However, some shielding materials have a high ferromagnetic metal content and poor PIM performance, and using these shielding materials will introduce new sources of signal interference. Therefore, copper foil with high purity, good conductivity, and high ductility has become the preferred shielding material for mobile electronic devices.

[0003] However, while pure copper foil has good conductivity and electrical shielding effect, its identical color on both sides and high metallic luster make it highly reflective of white light and lasers. This reduces the ability of optical equipment to identify and locate the shielding material, making it difficult to accurately locate and assemble various components through optical recognition systems on automated production lines, thus reducing production efficiency and accuracy.

[0004] To meet the ever-increasing electromagnetic shielding performance requirements and production demands of the electronics industry, the market urgently needs a new type of shielding material that possesses both excellent electrical shielding performance and suitable magnetic shielding performance, while also facilitating convenient optical positioning and assembly. This material should have superior electromagnetic shielding effects, effectively blocking interference from environmental electromagnetic waves to the internal circuits of electronic devices; it should also have a unique silver-gray appearance, facilitating accurate identification by optical positioning systems and improving production assembly efficiency and precision.

[0005] For the reasons mentioned above, it is necessary to develop a method for preparing silver-gray electromagnetic shielding copper foil. The silver-gray electromagnetic shielding copper foil prepared by this method has a unique silver-gray appearance on one or both sides, and at the same time, it has good passive intermodulation (PIM) performance and good electromagnetic shielding performance, which meets the requirements of the appearance of the optical identification and positioning system of the automated assembly line and the electromagnetic shielding performance of the electronic equipment. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a silver-gray electromagnetic shielding copper foil and its preparation method, thereby resolving the issues raised in the background section.

[0007] In a first aspect, embodiments of the present invention provide the following technical solution: a method for manufacturing a silver-gray electromagnetic shielding copper foil, comprising:

[0008] S1. Provide copper foil to be processed, and sequentially perform surface degreasing and acid solution cleaning processes on the copper foil to be processed to obtain processed copper foil;

[0009] S2. Provide a blackening treatment solution, immerse the copper foil in the blackening treatment solution for blackening treatment, and obtain blackened copper foil;

[0010] S3. The blackened copper foil is placed in a metal plating solution for surface electroplating treatment to electroplat a silver-gray magnetic shielding alloy layer on the surface of the blackened copper foil to obtain electroplated copper foil.

[0011] S4. The electroplated copper foil is subjected to anti-oxidation treatment to form a protective film on the surface of the electroplated copper foil, so as to obtain a silver-gray electromagnetic shielding copper foil.

[0012] Compared with the prior art, the beneficial effects of this application are as follows: the silver-gray electromagnetic shielding copper foil prepared by the manufacturing method provided by this invention has a unique silver-gray appearance on one or both sides, and the color system CIE Lab of its silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10. At the same time, it has good passive intermodulation performance, with a passive intermodulation PIM value of (-150)-(-70) dBm, and has good shielding performance, which meets the requirements of the appearance of the optical identification and positioning system of the automated assembly line and the electromagnetic shielding performance of the electronic equipment.

[0013] Preferably, in step S1, the copper foil to be processed is a flexible electrolytic copper foil or a flexible rolled copper foil with a thickness of 6µm-35µm.

[0014] Preferably, in step S2, the blackening treatment solution comprises 5 g / L-60 g / L copper salt, 40 g / L-200 g / L sulfuric acid, and 2 g / L-10 g / L blackening treatment additive. The blackening treatment additive is two or three of hydrogen peroxide, acetic acid, disodium ethylenediaminetetraacetate, triethanolamine, tetrahydroxypropyl ethylenediamine, N-methyldiethanolamine, and sodium silicate. In step S2, the temperature of the blackening treatment solution is 35℃-60℃, and the time is 3s-15s.

[0015] Preferably, step S2 may further consist of: immersing the copper foil in the blackening treatment solution, using one or both sides of the copper foil as the anode surface, placing a DSA anode parallel to the anode surface of the copper foil, and applying current to the anode surface and cathode plate for electrochemical blackening treatment. The current density of the electrochemical blackening treatment is 0.1 A / dm³. 2 -0.5A / dm 2 .

[0016] Preferably, in step S3, the silver-gray magnetic shielding alloy layer is composed of at least two nickel-based metal / alloy layers selected from Ni, Ni-Cu, Ni-Cr, Ni-Mo, Ni-P, Ni-P-Cr, and Ni-Mo-Cr.

[0017] Preferably, in step S3, the metal plating solution comprises a main metal component, an alloy component, a stabilizing component, a complexing component, and a conductive salt, wherein the main metal component is 2 g / L - 180 g / L Ni. 2+ The alloy composition is 1g / L-5g / L Cu. 2+ , 4g / L-50g / L CrO3, 6g / L-45g / L Cr 3+ 0.5g / L-8g / L MoO4 2- 0.5g / L-10g / L H2PO2 - The stable component is one or two of the following: thiocyanate, sodium saccharin, coumarin, and boric acid (0.5 g / L-40 g / L); the complexing component is one or two of the following: phosphate, pyrophosphate, formate, acetate, citrate, and tartrate (20 g / L-160 g / L); and the conductive salt is any one of the following: sulfate, chloride, and nitrate of sodium, potassium, or ammonium (20 g / L-300 g / L).

[0018] Preferably, in step S3, the Ni content in the silver-gray magnetic shielding alloy layer is 70wt.%-95wt.%, and the Ni content in the nickel metal / nickel-based alloy layer constituting the silver-gray magnetic shielding alloy layer is 60wt.%-100wt.%.

[0019] Preferably, in step S3, the plating bath temperature is 20℃-65℃, the pH value of the plating bath is 2.0-4.5, and the current density is 0.2A / dm³. 2 -6A / dm 2 Electroplating time: 1s-15s.

[0020] Preferably, step S4 specifically comprises:

[0021] An organic anti-oxidation solution is immersed, sprayed, or brushed onto the surface of the electroplated copper foil, and then dried by heating or blowing air to form a protective film on the surface of the electroplated copper foil. The organic anti-oxidation solution is an aqueous solution of any one of benzotriazole, methylbenzotriazole, phytic acid, and tannic acid with a concentration of 0.1wt.%-3.0wt.%.

[0022] Secondly, embodiments of the present invention also provide the following technical solution: a silver-gray electromagnetic shielding copper foil, wherein the silver-gray electromagnetic shielding copper foil is prepared by the manufacturing method of the silver-gray electromagnetic shielding copper foil described above, wherein one or both sides of the silver-gray electromagnetic shielding copper foil have a silver-gray appearance, and the color system CIE Lab of its silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10, and the passive intermodulation PIM value is (-150)-(-70) dBm. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart illustrating the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in Embodiment 1 of the present invention;

[0025] Figure 2 This is a structural diagram of the silver-gray electromagnetic shielding copper foil manufactured using the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in Embodiment 1.

[0026] Figure 3 The image shows a surface electron microscope (TEM) image of the blackened copper foil in the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in Embodiment 1 of the present invention.

[0027] Figure 4 An electron microscope image of the electroplated surface of the silver-gray magnetic shielding alloy layer in the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in Embodiment 1 of the present invention.

[0028] Figure 5 This is a structural diagram of the silver-gray electromagnetic shielding copper foil manufactured using the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in this embodiment 2.

[0029] Figure 6 This is a structural diagram of the silver-gray electromagnetic shielding copper foil manufactured using the manufacturing method of the silver-gray electromagnetic shielding copper foil provided in this embodiment 3.

[0030] Explanation of reference numerals in the attached figures:

[0031]

[0032] The embodiments of the present invention will be further described below with reference to the accompanying drawings. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.

[0034] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0037] Example 1

[0038] like Figure 1 , Figure 2 As shown, the first embodiment of the present invention provides a method for manufacturing a silver-gray electromagnetic shielding copper foil, comprising:

[0039] S1. Provide copper foil to be processed, and sequentially perform surface degreasing and acid solution cleaning processes on the copper foil to be processed to obtain processed copper foil;

[0040] Specifically, in step S1, the copper foil to be treated is a flexible electrolytic copper foil with a thickness of 8.5 µm. The copper foil to be treated has a smooth surface profile on both sides. In this step, by performing corresponding surface degreasing and acidic solution cleaning on the copper foil to be treated, impurities and stains on the surface of the copper foil to be treated can be effectively removed, so as to facilitate the subsequent blackening treatment and electroplating process.

[0041] S2. Provide a blackening treatment solution, immerse the copper foil in the blackening treatment solution to perform chemical blackening treatment on both sides of the copper foil to obtain blackened copper foil 1;

[0042] like Figure 3 As shown, specifically, by chemically blackening both sides of the copper foil, a large number of energy-absorbing trap structures are generated on the surface of the double-sided copper layer through chemical action, which increases the absorption capacity of the double-sided copper layer surface for visible light and electromagnetic waves, reduces the brightness of the double-sided copper layer surface of the treated copper foil, and enhances the shielding effect of the copper foil against electromagnetic waves.

[0043] In this embodiment, the blackening treatment solution includes 30g / L-35g / L copper chloride, 80g / L-90g / L sulfuric acid, 2g / L-4g / L hydrogen peroxide, and 0.5g / L-1.5g / L sodium silicate. The blackening treatment is an immersion treatment, the solution temperature is 40℃-45℃, and the treatment time is 10s-12s.

[0044] S3. The blackened copper foil 1 is placed in a metal plating solution for surface electroplating treatment, so as to electroplat a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1 to obtain electroplated copper foil.

[0045] like Figure 4 As shown, specifically, by electroplating the blackened copper foil 1, a silver-gray magnetic shielding alloy layer 2 is formed on the surface of the blackened copper foil 1. It is composed of a magnetic silver-gray nickel metal / nickel-based alloy electroplating layer, so that the copper foil has a uniform silver-gray surface. At the same time, the nickel metal / nickel-based alloy plating layer can form a continuous barrier, which can effectively absorb electromagnetic waves, achieve a good shielding effect, and give the shielding copper foil good passive intermodulation (PIM) performance.

[0046] In this embodiment, a silver-gray magnetic shielding alloy layer 2 is electroplated on any side of the blackened copper foil 1 to obtain an electroplated surface of the silver-gray magnetic shielding alloy layer 2.

[0047] In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of two alloys: Ni-Cu and Ni-P-Cr.

[0048] In this embodiment, the inner layer of the silver-gray magnetic shielding alloy layer 2 is a first Ni-Cu alloy layer 21, and the outer layer is a Ni-P-Cr alloy layer 22.

[0049] In this embodiment, in step S3, the metal plating solution of the first Ni-Cu alloy layer 21 includes 30g / L-35g / L Ni 2+ (Nickel sulfate), 3g / L - 5g / L Cu 2+ Copper sulfate, 25g / L-30g / L boric acid, 25g / L-35g / L sodium acetate, 30g / L-50g / L sodium sulfate; plating bath temperature 30℃-35℃; plating bath pH 3.0±0.4; current density 1A / dm³. 2 -3A / dm 2 Electroplating time: 3-5 seconds.

[0050] In this embodiment, in step S3, the thickness of the first Ni-Cu alloy layer 21 obtained by electroplating is 30nm-35nm, and the Ni content in the first Ni-Cu alloy layer 21 is 87wt.%-93wt.%.

[0051] In this embodiment, in step S3, the metal plating solution of the Ni-P-Cr alloy layer 22 includes 2g / L-6g / L Ni. 2+ The plating solution consists of: nickel sulfate (6 g / L - 10 g / L), CrO3 (3.5 g / L - 7.5 g / L), NaH2PO2 (28 g / L - 34 g / L), boric acid (1 g / L - 3 g / L), sodium formate (70 g / L - 80 g / L), and potassium sulfate (80 g / L - 120 g / L). The plating solution temperature is 20℃-30℃, pH is 3.0-3.2, and the current density is 0.5 A / dm³. 2 -1.0A / dm 2 Electroplating time: 5s - 12s.

[0052] In this embodiment, in step S3, the thickness of the Ni-P-Cr alloy layer 22 obtained by electroplating is 10nm-20nm, and the Ni content in the Ni-P-Cr alloy layer 22 is 62wt.%-75wt.%.

[0053] S4. The electroplated copper foil is subjected to anti-oxidation treatment to form a protective film 3 on the surface of the electroplated copper foil, so as to obtain a silver-gray electromagnetic shielding copper foil.

[0054] Specifically, the anti-oxidation protective film 3 can form a dense protective film 3 on the surface of the copper foil, preventing external factors such as oxygen and moisture from directly contacting the copper foil, thereby slowing down the oxidation rate of copper and further improving the passive intermodulation (PIM) performance of the shielded copper foil.

[0055] In this embodiment, the anti-oxidation treatment specifically involves immersing the sample in a 0.2 wt.% benzotriazole solution for 10-12 seconds, followed by hot air drying.

[0056] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on the electroplated surface of its silver-gray magnetic shielding alloy layer 2. The color CIE Lab of the silver-gray surface is L: 70-75, a: 1.3-1.8, b: 7.0-8.8, and the PIM value is (-130)-(-100) dBm, which has a good shielding effect.

[0057] Example 2

[0058] like Figure 5 As shown, the second embodiment of the present invention provides a method for manufacturing a silver-gray electromagnetic shielding copper foil, comprising:

[0059] S1. Provide copper foil to be processed, and sequentially perform surface degreasing and acid solution cleaning processes on the copper foil to be processed to obtain processed copper foil;

[0060] Specifically, in step S1, the copper foil to be treated is a flexible electrolytic copper foil with a thickness of 11 µm. The copper foil to be treated has a smooth surface profile on both sides. In this step, by performing corresponding surface degreasing and acidic solution cleaning on the copper foil to be treated, impurities and stains on the surface of the copper foil to be treated can be effectively removed, so as to facilitate the subsequent blackening treatment and electroplating process.

[0061] S2. Provide a blackening treatment solution, immerse the copper foil to be treated in the blackening treatment solution, and use any side of the copper foil to be treated as the anode side to perform electrochemical blackening treatment on the anode side of the copper foil to obtain blackened copper foil 1.

[0062] Specifically, by performing electrochemical blackening treatment on the anode surface of the copper foil, a large number of energy-absorbing trap structures are generated on the surface of the copper layer of the anode surface through electrochemical action. This increases the absorption capacity of the copper layer surface of the anode surface for visible light and electromagnetic waves, reduces the brightness of the copper layer surface of the copper foil, and enhances the shielding effect of the copper foil against electromagnetic waves.

[0063] In this embodiment, the blackening treatment solution comprises 15 g / L-30 g / L copper sulfate, 60 g / L-70 g / L sulfuric acid, 5 g / L-8 g / L disodium ethylenediaminetetraacetate (EDTA), and 1.5 g / L-2 g / L triethanolamine. The temperature of the blackening treatment solution is 35℃-45℃, and the current density is 0.1 A / dm³. 2 -0.2A / dm 2 The processing time is 5-8 seconds.

[0064] S3. The blackened copper foil 1 is placed in a metal plating solution to perform surface electroplating treatment on the anode surface, so as to electroplat a silver-gray magnetic shielding alloy layer 2 on the anode surface of the blackened copper foil 1 to obtain electroplated copper foil.

[0065] In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of a Ni metal layer 23 and two alloy layers, Ni-P and Ni-Cr.

[0066] In this embodiment, the silver-gray magnetic shielding alloy layer 2 consists of a Ni metal layer 23, a Ni-P alloy layer 24, and a Ni-Cr alloy layer 25, arranged sequentially from the inner to the outer layer.

[0067] In this embodiment, in step S3, the metal plating solution of the Ni metal layer 23 includes 30g / L - 35g / L Ni. 2+ Nickel sulfamate, 0.5 g / L - 1.0 g / L coumarin, 25 g / L - 35 g / L boric acid, 25 g / L - 35 g / L sodium acetate, 100 g / L - 180 g / L sodium sulfate; plating bath temperature 30℃-55℃, plating bath pH 4.0±0.5, current density 1.5 A / dm³ 2 -2A / dm 2 Electroplating time: 3-5 seconds.

[0068] In this embodiment, in step S3, the thickness of the Ni metal layer 23 obtained by electroplating is 20nm-40nm, and the Ni content in the Ni metal layer 23 is 98wt.%-100wt.%.

[0069] In this embodiment, in step S3, the metal plating solution of the Ni-P alloy layer 24 includes 10 g / L - 15 g / L Ni. 2+ (Nickel sulfate), 2 g / L - 4 g / L H2PO2 - The plating solution contained sodium hypophosphite, 1.0±0.2 g / L sodium saccharin, 25 g / L-35 g / L boric acid, 25 g / L-35 g / L sodium acetate, and 100 g / L-180 g / L sodium sulfate. The plating bath temperature was 35℃-45℃, the pH value was 3.5±0.5, and the current density was 0.5 A / dm³. 2 -1.0A / dm 2 Electroplating time: 3-5 seconds.

[0070] In this embodiment, in step S3, the thickness of the Ni-P alloy layer 24 obtained by electroplating is 15nm-25nm, and the Ni content in the Ni-P alloy layer 24 is 70 wt.%-80 wt.%.

[0071] In this embodiment, in step S3, the metal plating solution of the Ni-Cr alloy layer 25 includes 0.5 g / L - 3 g / L Ni. 2+ (Nickel sulfate), 2g / L - 8g / L Cr 3+ (Chromium sulfate), 25g / L - 35g / L boric acid, 25g / L - 35g / L sodium acetate, 30g / L - 35g / L sodium sulfate; plating bath temperature 25℃-35℃; plating bath pH 1.0-2.5; current density 0.5A / dm³ 2 -2.0A / dm 2 Electroplating time: 1.5s - 3s.

[0072] In this embodiment, in step S3, the thickness of the Ni-Cr alloy layer 25 obtained by electroplating is 5nm-15nm, and the Ni content in the Ni-Cr alloy layer 25 is 60wt.%-70wt.%.

[0073] S4. The electroplated copper foil is subjected to anti-oxidation treatment to form an anti-oxidation protective film 3 on the surface of the copper foil, so as to obtain a silver-gray electromagnetic shielding copper foil.

[0074] In this embodiment, the anti-oxidation treatment specifically involves immersing the sample in a 2.0 wt.% phytic acid solution for 10-12 seconds, followed by hot air drying.

[0075] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on the electroplated surface of its silver-gray magnetic shielding alloy layer 2. The color system of the silver-gray surface is CIE Lab: L: 66-73, a: 0.9-2.5, b: 6.0-8.0, and the PIM value is (-110)-(-70) dBm, which has a good shielding effect.

[0076] Example 3

[0077] like Figure 6 As shown, the third embodiment of the present invention provides a method for manufacturing a silver-gray electromagnetic shielding copper foil, comprising:

[0078] S1. Provide copper foil to be processed, and sequentially perform surface degreasing and acid solution cleaning processes on the copper foil to be processed to obtain processed copper foil;

[0079] Specifically, in step S1, the copper foil to be processed is a flexible rolled copper foil with a thickness of 12 µm, and has a smooth surface profile on both sides.

[0080] S2. Provide a blackening treatment solution, immerse the copper foil in the blackening treatment solution to perform chemical blackening treatment on both sides of the copper foil to obtain blackened copper foil 1;

[0081] In this embodiment, the blackening treatment solution includes 5 g / L-15 g / L copper sulfate, 120 g / L-150 g / L sulfuric acid, 3 g / L-6 g / L hydrogen peroxide, 1.0 ± 0.2 g / L tetrahydroxypropyl ethylenediamine, and 1 g / L-2 g / L sodium silicate. The temperature of the blackening treatment solution is 25℃-35℃, and the treatment time is 3s-6s.

[0082] S3. The blackened copper foil 1 is placed in a metal plating solution for surface electroplating treatment, so as to electroplat a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1 to obtain electroplated copper foil.

[0083] In this embodiment, a silver-gray magnetic shielding alloy layer 2 is electroplated on both sides of the blackened copper foil 1 to obtain the electroplated surface of the silver-gray magnetic shielding alloy layer 2.

[0084] In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of three alloy layers: Ni-Cu, Ni-Mo, and Ni-Mo-Cr.

[0085] In this embodiment, the silver-gray magnetic shielding alloy layer 2 consists of a second Ni-Cu alloy layer 26, a Ni-Mo alloy layer 27, and a Ni-Mo-Cr alloy layer 28, arranged sequentially from the inner to the outer layer.

[0086] In this embodiment, in step S3, the metal plating solution of the second Ni-Cu alloy layer 26 includes 30g / L-35g / L Ni 2+ (Nickel sulfate), 1g / L - 2g / L Cu 2+ Copper sulfate, 25 g / L - 30 g / L boric acid, 100 g / L - 140 g / L sodium citrate, 30 g / L - 50 g / L sodium sulfate; plating bath temperature 45℃-65℃; plating bath pH 4.0±0.5; current density 4 A / dm³ 2 -6A / dm 2 Electroplating time is 1-3 seconds.

[0087] In this embodiment, in step S3, the thickness of the second Ni-Cu alloy layer 26 obtained by electroplating is 40nm-50nm, and the Ni content in the second Ni-Cu alloy layer 26 is 89wt.%-96wt.%.

[0088] In this embodiment, in step S3, the metal plating solution of the Ni-Mo alloy layer 27 includes 15 g / L - 20 g / L Ni. 2+ (Nickel sulfate), 5 g / L - 8 g / L MoO4 2-Sodium molybdate, 30g / L-50g / L ammonium acetate, 50g / L-100g / L sodium citrate, 20g / L-30g / L potassium sulfate; plating bath temperature 35℃-45℃; plating bath pH 3.0-3.6; current density 2A / dm³ 2 -4A / dm 2 Electroplating time: 3-5 seconds.

[0089] In this embodiment, in step S3, the thickness of the Ni-Mo alloy layer 27 obtained by electroplating is 20nm-25nm, and the Ni content in the Ni-Mo alloy layer 27 is 93wt.%-98wt.%.

[0090] In this embodiment, in step S3, the metal plating solution of the Ni-Mo-Cr alloy layer 28 includes 2 g / L - 4 g / L Ni. 2+ (Nitrogen sulfate), 15g / L -25g / L Cr 3+ (Chromium sulfate), 4 g / L - 6 g / L MoO4 2- Sodium molybdate, 20 g / L - 25 g / L boric acid, 30 g / L - 50 g / L sodium phosphate, 20 g / L - 30 g / L sodium sulfate; plating bath temperature 20℃-40℃; plating bath pH 2.0±0.5; current density 1.0 A / dm³ 2 -1.5A / dm 2 Electroplating time: 4-6 seconds.

[0091] In this embodiment, in step S3, the thickness of the Ni-Mo-Cr alloy layer 28 obtained by electroplating is 10nm-20nm, and the Ni content in the Ni-Mo-Cr alloy layer 28 is 63wt.%-76wt.%.

[0092] S4. The electroplated copper foil is subjected to anti-oxidation treatment to form an anti-oxidation protective film 3 on the surface of the copper foil, so as to obtain a silver-gray electromagnetic shielding copper foil.

[0093] In this embodiment, the anti-oxidation treatment specifically involves immersing the sample in a 3.0 wt.% tannic acid solution for 30-60 seconds, followed by hot air drying.

[0094] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on both sides. The color CIE Lab of the silver-gray surface is L: 76-84, a: 2.3-3.6, b: 5.5-7.5, and the PIM value is (-150)-(-90) dBm, which has a good shielding effect.

[0095] In another embodiment of the present invention, a silver-gray electromagnetic shielding copper foil is provided. The silver-gray electromagnetic shielding copper foil is prepared by the manufacturing method of the silver-gray electromagnetic shielding copper foil in the above embodiment. One or both sides of the silver-gray electromagnetic shielding copper foil have a silver-gray appearance. The color system CIE Lab of its silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10, and the passive intermodulation PIM value is (-150)-(-70) dBm.

[0096] It should be noted that, in order to further verify the effects of the present invention, the present invention also provides the following comparative examples for corresponding comparative explanation.

[0097] Comparative Example 1

[0098] Comparative Example 1 provides a method for manufacturing silver-gray electromagnetic shielding copper foil. The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not perform step S3 in Example 1, which involves immersing the blackened copper foil 1 in a metal plating solution for surface electroplating treatment, so as to electroplat a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1 to obtain the electroplated copper foil.

[0099] The electromagnetic shielding copper foil prepared by the preparation method provided in Comparative Example 1 has a uniform dark brownish-red surface with a CIE Lab color scheme of L: 45-53, a: 9-17, b: 2-6 and a PIM value of (-60)-(-30) dBm.

[0100] Comparative Example 2

[0101] Comparative Example 2 provides a method for manufacturing silver-gray electromagnetic shielding copper foil. The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 does not perform the process of step S2 in Example 1, which involves immersing the copper foil in the blackening solution for blackening treatment to obtain blackened copper foil 1.

[0102] The electromagnetic shielding copper foil prepared by the preparation method provided in Comparative Example 2 has a bright silver-gray surface on the electroplated surface of its silver-gray magnetic shielding alloy layer 2. The color CIE Lab of the silver-gray surface is L: 81-90, a: 1.3-3.8, b: 6.0-7.5, and the PIM value is (-100)-(-30) dBm.

[0103] Comparative Example 3

[0104] Comparative Example 3 provides a method for manufacturing a silver-gray electromagnetic shielding copper foil. The difference between Comparative Example 3 and Example 2 is that a Ni metal layer 23 is electroplated on the surface of the blackened copper foil 1, and the outer layer is not electroplated with a Cr-containing nickel-based alloy layer.

[0105] The electromagnetic shielding copper foil prepared by the preparation method provided in Comparative Example 3 has a uniform and bright silver-gray surface on the electroplated surface of the silver-gray magnetic shielding alloy layer 2. The color system of the silver-gray surface is CIE Lab: L: 81-87, a: 0.6-1.1, b: 5.3-7.0, and the PIM value is (-70)-(-50) dBm.

[0106] Therefore, according to the comparison, compared with Example 1, Comparative Example 1 did not perform step S3 of electroplating the silver-gray magnetic shielding alloy layer 2, and the surface of the electromagnetic shielding copper foil obtained did not present an aesthetically pleasing silver-gray color. The CIE Lab color system of the copper foil surface was significantly different in L, a, and b values ​​compared with the silver-gray electromagnetic shielding copper foil obtained in Example 1, and its electromagnetic shielding effectiveness was relatively poor. Compared with Example 2, Comparative Example 2 did not perform step S2 of blackening treatment, and the prepared silver-gray electromagnetic shielding copper foil had a higher brightness. The L value in the CIE Lab color system of the copper foil surface increased, while the a and b values ​​decreased. The bonding force between the silver-gray magnetic shielding alloy layer 2 and the copper foil substrate deteriorated, the electromagnetic shielding performance decreased, and the fluctuation range widened. Compared with Example 2, Comparative Example 3 only electroplated a layer of Ni metal layer 23, and did not electroplat the outer layer with a Cr-containing nickel-based alloy layer. The prepared silver-gray electromagnetic shielding copper foil had a higher brightness, but the CIE Lab color system of its silver-gray surface did not meet the requirements, and its electromagnetic shielding effectiveness was poor.

[0107] In summary, the silver-gray electromagnetic shielding copper foil prepared by the manufacturing method provided by this invention has a unique silver-gray appearance on one or both sides. The color CIE Lab of its silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10. At the same time, it has good passive intermodulation performance, with a passive intermodulation PIM value of (-150)-(-70) dBm, and has good shielding performance, which meets the requirements of the appearance of the optical identification and positioning system of the automated assembly line and the electromagnetic shielding performance of electronic equipment.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a silver-gray electromagnetic shielding copper foil, characterized in that, include: S1. Provide copper foil to be processed, and sequentially perform surface degreasing and acid solution cleaning processes on the copper foil to be processed to obtain processed copper foil; S2. Provide a blackening treatment solution, immerse the copper foil in the blackening treatment solution for blackening treatment, and obtain blackened copper foil; S3. The blackened copper foil is placed in a metal plating solution for surface electroplating treatment to electroplat a silver-gray magnetic shielding alloy layer on the surface of the blackened copper foil to obtain electroplated copper foil. S4. The electroplated copper foil is subjected to anti-oxidation treatment to form a protective film on the surface of the electroplated copper foil to obtain a silver-gray electromagnetic shielding copper foil. In step S2, the blackening treatment solution includes 5 g / L-60 g / L copper salt, 40 g / L-200 g / L sulfuric acid, and 2 g / L-10 g / L blackening treatment additive. The blackening treatment additive is two or three of hydrogen peroxide, acetic acid, disodium ethylenediaminetetraacetate, triethanolamine, tetrahydroxypropyl ethylenediamine, N-methyldiethanolamine, and sodium silicate. In step S2, the temperature of the blackening treatment solution is 35℃-60℃ and the time is 3s-15s. Alternatively, step S2 may involve immersing the copper foil in the blackening solution, using one or both sides of the copper foil as the anode surface, placing a DSA anode parallel to the anode surface of the copper foil, and applying current to the anode surface and cathode plate for electrochemical blackening treatment. The current density for electrochemical blackening treatment is 0.1 A / dm³. 2 -0.5A / dm 2 ; In step S3, the silver-gray magnetic shielding alloy layer is composed of at least two of Ni-Cu, Ni-Cr, Ni-Mo, Ni-P, Ni-P-Cr, and Ni-Mo-Cr.

2. The method for manufacturing silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that, In step S1, the copper foil to be processed is a flexible electrolytic copper foil or a flexible rolled copper foil with a thickness of 6µm-35µm.

3. The method for manufacturing silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that, In step S3, the metal plating bath comprises a main metal component, an alloy component, a stabilizing component, a complexing component, and a conductive salt, wherein the main metal component is 2 g / L - 180 g / L Ni. 2+ The alloy composition is 1g / L-5g / L Cu. 2+ , 4g / L-50g / L CrO3, 6g / L-45g / L Cr 3 + 0.5g / L-8g / L MoO4 2- 0.5g / L-10g / L H2PO2 - The stable component is one or two of the following: thiocyanate, sodium saccharin, coumarin, and boric acid (0.5 g / L-40 g / L); the complexing component is one or two of the following: phosphate, pyrophosphate, formate, acetate, citrate, and tartrate (20 g / L-160 g / L); and the conductive salt is any one of the following: sulfate, chloride, and nitrate of sodium, potassium, or ammonium (20 g / L-300 g / L).

4. The method for manufacturing silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that, In step S3, the Ni content in the silver-gray magnetic shielding alloy layer is 70wt.%-95wt.%.

5. The method for manufacturing silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that, In step S3, the plating bath temperature is 20℃-65℃, the pH value of the plating bath is 2.0-4.5, and the current density is 0.2A / dm³. 2 -6A / dm 2 Electroplating time: 1s-15s.

6. The method for manufacturing silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that, Step S4 is as follows: An organic anti-oxidation solution is immersed, sprayed, or brushed onto the surface of the electroplated copper foil, and then dried by heating or blowing air to form a protective film on the surface of the electroplated copper foil. The organic anti-oxidation solution is an aqueous solution of any one of benzotriazole, methylbenzotriazole, phytic acid, and tannic acid with a concentration of 0.1wt.%-3.0wt.%.

7. A silver-gray electromagnetic shielding copper foil, characterized in that, The silver-gray electromagnetic shielding copper foil is prepared by the manufacturing method of silver-gray electromagnetic shielding copper foil as described in any one of claims 1-6. One or both sides of the silver-gray electromagnetic shielding copper foil have a silver-gray appearance, and the color system CIE Lab of its silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10, and the passive intermodulation PIM value is (-150)-(-70) dBm.

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