Silver gray electromagnetic shielding copper foil and preparation method thereof

Abstract

The invention provides a silver gray electromagnetic shielding copper foil and a preparation method thereof, and the preparation method of the silver gray electromagnetic shielding copper foil comprises the following steps: providing a to-be-treated copper foil, and sequentially carrying out surface oil removal and acid solution cleaning processes on the to-be-treated copper foil to obtain a treated copper foil; providing a blackening treatment solution, and soaking the treated copper foil in the blackening treatment solution for blackening treatment to obtain a blackened copper foil; the blackened copper foil is put into a metal plating solution to be subjected to surface electroplating treatment, so that a silver gray magnetic shielding alloy layer is electroplated on the surface of the blackened copper foil, and an electroplated copper foil is obtained; the electroplating copper foil is subjected to anti-oxidation treatment, so that a protective film is formed on the surface of the electroplating copper foil, and the silver gray electromagnetic shielding copper foil is obtained.The silver gray electromagnetic shielding copper foil prepared through the method has the unique silver gray appearance on one face or two faces, meanwhile, the passive intermodulation performance is good, and the shielding performance is good; and the requirements of an automatic assembly line optical identification positioning system on the appearance and electronic equipment on the electromagnetic shielding performance are met.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and specifically relates to a silver-grey electromagnetic shielding copper foil and a preparation method thereof. Background Art

[0002] With the rapid development of science and technology, products in the electronic field such as 3C electronics and smart wearable devices are constantly being innovated. These electronic devices are increasingly developing in the direction of miniaturization, integration, and high performance. In this process, the circuit density inside the equipment continues to increase, and the electromagnetic interference problem between various electronic components has become more and more prominent. If the interference of environmental electromagnetic waves on the panel circuit cannot be effectively shielded, it will have a serious impact. By using shielding materials to shield the interference of environmental electromagnetic waves on the panel circuit, the integrity of circuit board signal transmission can be improved, and the performance, stability and reliability of the equipment can be improved. However, some shielding materials have a high content of ferromagnetic metals and poor PIM performance. The use of these shielding materials will introduce new sources of signal interference. Therefore, copper foil with higher purity, better conductivity and higher ductility has become the first choice for shielding materials for mobile electronic devices.

[0003] However, although pure copper foil has good conductivity and electrical shielding effect, it has the same color on both sides and has a high metallic luster, and has a strong reflective ability to white light and laser, which will reduce the recognition and positioning of shielding materials by optical equipment, and is not conducive to accurately positioning and assembling various components through optical recognition systems on automated production lines, reducing production efficiency and precision.

[0004] In order to meet the ever-increasing electromagnetic shielding performance requirements and production needs of the electronic equipment industry, the market urgently needs a new type of shielding material that has both good electrical shielding performance and suitable magnetic shielding performance, and can also facilitate optical positioning and assembly. The material should have excellent electromagnetic shielding effect, effectively blocking the interference of environmental electromagnetic waves on the internal circuits of electronic equipment; it should have a unique silver-gray appearance, which is convenient for accurate identification by the optical positioning system, and improve production and assembly efficiency and accuracy.

[0005] Due to the above reasons, it is necessary to develop a method for preparing a 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 side or both sides, and its passive intermodulation (PIM) performance is good, and it has good electromagnetic shielding performance, which meets the requirements of the optical recognition and positioning system of the automated assembly line for its appearance and the electromagnetic shielding performance of electronic equipment. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a silver-gray electromagnetic shielding copper foil and a preparation method thereof to solve the problems raised in the above background technology.

[0007] In a first aspect, an embodiment of the present invention provides the following technical solution, a method for manufacturing a silver-gray electromagnetic shielding copper foil, comprising: S1. providing a copper foil to be treated, and sequentially performing a surface degreasing process and an acid solution cleaning process on the copper foil to be treated to obtain a treated copper foil; S2, providing a blackening treatment liquid, and immersing the treated copper foil in the blackening treatment liquid for blackening treatment to obtain a blackened copper foil; S3, placing the blackened copper foil in a metal plating solution for surface electroplating treatment, so as to electroplate a silver-gray magnetic shielding alloy layer on the surface of the blackened copper foil to obtain an electroplated copper foil; S4. Performing an anti-oxidation treatment on the electroplated copper foil to form a protective film on the surface of the electroplated copper foil to obtain a silver-gray electromagnetic shielding copper foil.

[0008] Compared with the prior art, the beneficial effects of the present application are as follows: the silver-gray electromagnetic shielding copper foil prepared by the manufacturing method provided by the present invention has a unique silver-gray appearance on one side 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, and at the same time, its passive intermodulation performance is good, and the passive intermodulation PIM value is (-150) - (-70) dBm, and it has good shielding performance, which meets the requirements of the optical recognition and positioning system of the automated assembly line for its appearance and the electromagnetic shielding performance of electronic equipment.

[0009] Preferably, in step S1, the copper foil to be treated is a flexible electrolytic copper foil or a flexible rolled copper foil with a thickness of 6µm-35µm.

[0010] Preferably, in step S2, the blackening treatment liquid includes 5g / L-60g / L copper salt, 40g / L-200g / L sulfuric acid, and 2g / L-10g / L blackening treatment additives, and the blackening treatment additives are two or three of hydrogen peroxide, acetic acid, disodium ethylenediaminetetraacetate, triethanolamine, tetrahydroxypropylethylenediamine, N-methyldiethanolamine, and sodium silicate. In step S2, the temperature of the blackening treatment liquid is 35°C-60°C and the time is 3s-15s.

[0011] Preferably, step S2 may also be: immersing the treated copper foil in the blackening treatment solution, using one or both sides of the treated copper foil as the anode surface, placing a DSA anode directly opposite to the anode surface of the treated copper foil in parallel, applying current to the anode surface and the cathode plate for electrochemical blackening treatment, and the current density of the electrochemical blackening treatment is 0.1A / dm 2 -0.5A / dm 2 .

[0012] Preferably, in step S3, the silver-gray magnetic shielding alloy layer is composed of at least two nickel-based metal / alloy layers of Ni, Ni-Cu, Ni-Cr, Ni-Mo, Ni-P, Ni-P-Cr, and Ni-Mo-Cr.

[0013] 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, and the main metal component is 2g / L-180g / 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 stabilizing component is one or two of 0.5g / L-40g / L thiocyanate, sodium saccharin, coumarin, and boric acid; the complexing component is one or two of 20g / L-160g / L phosphate, pyrophosphate, formate, acetate, citrate, and tartrate; the conductive salt is any one of 20g / L-300g / L sodium, potassium, and ammonium sulfate, chloride, and nitrate.

[0014] Preferably, in step S3, the Ni content in the silver-grey magnetic shielding alloy layer is 70wt.%-95wt.%, and the Ni content in the nickel metal / nickel-based alloy layer constituting the silver-grey magnetic shielding alloy layer is 60wt.%-100wt.%.

[0015] Preferably, in step S3, the plating solution temperature is 20°C-65°C, the plating solution pH value is 2.0-4.5, and the current density is 0.2A / dm 2 -6A / dm 2 , electroplating time 1s-15s.

[0016] Preferably, the step S4 is specifically as follows: The surface of the electroplated copper foil is immersed in, sprayed with, or brushed with an organic anti-oxidation solution, and then a protective film is formed on the surface of the electroplated copper foil by heating or air drying. 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.%.

[0017] In a second aspect, an embodiment of the present invention also provides 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 as 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 the 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 A flow chart of a method for manufacturing a silver-gray electromagnetic shielding copper foil provided in Embodiment 1 of the present invention; Figure 2 This is a structural diagram of a silver-gray electromagnetic shielding copper foil manufactured by the method for manufacturing the silver-gray electromagnetic shielding copper foil provided in the first embodiment; Figure 3 This is a surface electron microscope image of the blackened copper foil in the method for manufacturing the silver-gray electromagnetic shielding copper foil provided in Example 1 of the present invention; Figure 4 An electron microscope image of the electroplated surface of the silver-gray magnetic shielding alloy layer in the method for manufacturing the silver-gray electromagnetic shielding copper foil provided in Example 1 of the present invention; Figure 5 This is a structural diagram of a silver-gray electromagnetic shielding copper foil manufactured by the method for manufacturing the silver-gray electromagnetic shielding copper foil provided in the second embodiment; Figure 6 This is a structural diagram of the silver-gray electromagnetic shielding copper foil manufactured by the method for manufacturing the silver-gray electromagnetic shielding copper foil provided in the third embodiment.

[0020] Description of reference numerals:

[0021] The embodiments of the present invention will be further described below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0023] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0026] Embodiment 1 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: S1. providing a copper foil to be treated, and sequentially performing a surface degreasing process and an acid solution cleaning process on the copper foil to be treated to obtain a treated copper foil; Specifically, in step S1, the copper foil to be treated is a flexible electrolytic copper foil with a thickness of 8.5 µm, and has a smooth surface profile on both sides of the copper foil to be treated. In this step, by performing corresponding surface degreasing and acid solution cleaning on the copper foil to be treated, impurities, stains, etc. on the surface of the copper foil to be treated can be effectively removed to facilitate subsequent blackening treatment and electroplating process.

[0027] S2, providing a blackening treatment liquid, immersing the treated copper foil in the blackening treatment liquid to perform chemical blackening treatment on both sides of the treated copper foil, so as to obtain a blackened copper foil 1; like Figure 3 As shown, specifically, by chemically blackening both sides of the treated copper foil, a large number of trap structures with energy absorption function are generated on the surface of the double-sided copper layer through chemical action, thereby increasing the absorption capacity of the double-sided copper layer surface to visible light and electromagnetic waves, reducing the brightness of the double-sided copper layer surface of the treated copper foil, and enhancing the shielding effect of the copper foil on electromagnetic waves.

[0028] In this embodiment, the blackening treatment liquid includes 30g / L-35g / L copper chloride, 80g / L-90 g / 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°C-45°C, and the treatment time is 10s-12s.

[0029] S3, placing the blackened copper foil 1 into a metal plating solution for surface electroplating treatment, so as to electroplate a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1, so as to obtain an electroplated copper foil; like Figure 4 As shown, specifically, the blackened copper foil 1 is electroplated to form a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1, which 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, and 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 make the shielding copper foil have good passive intermodulation (PIM) performance.

[0030] In this embodiment, a silver-grey magnetic shielding alloy layer 2 is electroplated on any one surface of the blackened copper foil 1 to obtain an electroplated surface of the silver-grey magnetic shielding alloy layer 2 .

[0031] In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of two alloys: Ni-Cu and Ni-P-Cr.

[0032] 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 .

[0033] 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, bath temperature 30℃-35℃, bath pH 3.0±0.4, current density 1A / dm 2 -3A / dm 2 , electroplating time 3-5 s.

[0034] In this embodiment, in step S3, the thickness of the first Ni—Cu alloy layer 21 obtained by electroplating is 30 nm-35 nm, and the Ni content in the first Ni—Cu alloy layer 21 is 87 wt.%-93 wt.%.

[0035] 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+ (nickel sulfate), 6g / L-10g / L CrO3, 3.5g / L -7.5 g / L NaH2PO2, 28g / L -34g / L boric acid, 1g / L-3g / L sodium formate, 70g / L-80g / L sodium citrate, 80g / L-120g / L potassium sulfate, bath temperature 20℃-30℃, bath pH 3.0-3.2, current density 0.5A / dm 2 -1.0A / dm 2 , electroplating time 5s -12s.

[0036] In this embodiment, in step S3, the thickness of the Ni—P—Cr alloy layer 22 obtained by electroplating is 10 nm-20 nm, and the Ni content in the Ni—P—Cr alloy layer 22 is 62 wt.%-75 wt.%.

[0037] S4, performing anti-oxidation treatment on the electroplated copper foil to form a protective film 3 on the surface of the electroplated copper foil to obtain a silver-gray electromagnetic shielding copper foil.

[0038] Specifically, the anti-oxidation protective film 3 can form a dense protective film 3 on the surface of the copper foil to prevent 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 shielding copper foil.

[0039] In this embodiment, the anti-oxidation treatment is specifically to immerse in a 0.2wt.% benzotriazole solution for 10s-12s and then blow dry with hot air.

[0040] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on the electroplated surface of the silver-gray magnetic shielding alloy layer 2, and the color of the silver-gray surface is CIE Lab 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.

[0041] Embodiment 2 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: S1. providing a copper foil to be treated, and sequentially performing a surface degreasing process and an acid solution cleaning process on the copper foil to be treated to obtain a treated copper foil; Specifically, in step S1, the copper foil to be treated is a flexible electrolytic copper foil with a thickness of 11 µm, and has a smooth surface profile on both sides of the copper foil to be treated. In this step, by performing corresponding surface degreasing and acid solution cleaning on the copper foil to be treated, impurities, stains, etc. on the surface of the copper foil to be treated can be effectively removed to facilitate subsequent blackening treatment and electroplating process.

[0042] S2, providing a blackening treatment liquid, immersing the treated copper foil in the blackening treatment liquid, using any side of the treated copper foil as an anode side, and performing an electrochemical blackening treatment on the anode side of the treated copper foil to obtain a blackened copper foil 1; Specifically, the anode surface of the treated copper foil is electrochemically blackened, and a large number of trap structures with energy-absorbing function are generated on the surface of the anode copper layer through electrochemical action, thereby increasing the absorption capacity of the anode copper layer to visible light and electromagnetic waves, reducing the brightness of the anode copper layer surface of the treated copper foil, and enhancing the shielding effect of the copper foil on electromagnetic waves.

[0043] In this embodiment, the blackening treatment solution includes 15g / L-30g / L copper sulfate, 60g / L-70g / L sulfuric acid, 5g / L-8g / L disodium ethylenediaminetetraacetate (EDTA), and 1.5g / L-2g / L triethanolamine. The temperature of the blackening treatment solution is 35°C-45°C, and the current density is 0.1A / dm 2 -0.2A / dm 2 , the processing time is 5s-8s.

[0044] S3, placing the blackened copper foil 1 in a metal plating solution to perform surface electroplating treatment on the anode surface, so as to electroplate a silver-gray magnetic shielding alloy layer 2 on the anode surface of the blackened copper foil 1, so as to obtain an electroplated copper foil; In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of a Ni metal layer 23 and two alloy layers of Ni—P and Ni—Cr.

[0045] In this embodiment, the silver-gray magnetic shielding alloy layer 2 includes a Ni metal layer 23 , a Ni—P alloy layer 24 , and a Ni—Cr alloy layer 25 from the inner layer to the outer layer.

[0046] In this embodiment, in step S3, the metal plating solution of the Ni metal layer 23 includes 30g / L-35g / LNi 2+ (nickel sulfamate), 0.5g / L -1.0g / L coumarin, 25g / L -35g / L boric acid, 25g / L -35g / L sodium acetate, 100g / L -180g / L sodium sulfate, bath temperature 30℃-55℃, bath pH 4.0±0.5, current density 1.5A / dm 2 -2A / dm 2 , electroplating time 3s -5s.

[0047] 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.%.

[0048] 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), 2g / L -4g / L H2PO2 - (sodium hypophosphite), 1.0±0.2 g / L saccharin sodium, 25g / L -35g / L boric acid, 25g / L -35 g / L sodium acetate, 100g / L -180g / L sodium sulfate, bath temperature 35℃-45℃, bath pH 3.5±0.5, current density 0.5A / dm 2 -1.0A / dm 2 , electroplating time 3-5 s.

[0049] In this embodiment, in step S3, the thickness of the Ni—P alloy layer 24 obtained by electroplating is 15 nm-25 nm, and the Ni content in the Ni—P alloy layer 24 is 70 wt.%-80 wt.%.

[0050] 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, bath temperature 25℃-35℃, bath pH 1.0-2.5, current density 0.5A / dm2 -2.0A / dm 2 , electroplating time 1.5s -3s.

[0051] In this embodiment, in step S3, the thickness of the Ni—Cr alloy layer 25 obtained by electroplating is 5 nm-15 nm, and the Ni content in the Ni—Cr alloy layer 25 is 60 wt.%-70 wt.%.

[0052] S4, performing anti-oxidation treatment on the electroplated copper foil to form an anti-oxidation protective film 3 on the surface of the copper foil to obtain a silver-gray electromagnetic shielding copper foil.

[0053] In this embodiment, the anti-oxidation treatment is specifically to immerse in a phytic acid solution with a concentration of 2.0 wt.% for 10s-12s, and then blow dry with hot air.

[0054] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on the electroplated surface of the silver-gray magnetic shielding alloy layer 2. The color 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.

[0055] Embodiment 3 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: S1. providing a copper foil to be treated, and sequentially performing a surface degreasing process and an acid solution cleaning process on the copper foil to be treated to obtain a treated copper foil; Specifically, in step S1, the copper foil to be treated is a flexible rolled copper foil with a thickness of 12 μm, and both sides of the copper foil to be treated have smooth surface profiles.

[0056] S2, providing a blackening treatment liquid, immersing the treated copper foil in the blackening treatment liquid to perform chemical blackening treatment on both sides of the treated copper foil, so as to obtain a blackened copper foil 1; In this embodiment, the blackening treatment solution includes 5g / L-15g / L copper sulfate, 120g / L-150g / L sulfuric acid, 3g / L-6g / L hydrogen peroxide, 1.0±0.2g / L tetrahydroxypropylethylenediamine, and 1g / L-2 g / L sodium silicate. The temperature of the blackening treatment solution is 25℃-35℃, and the treatment time is 3s-6s.

[0057] S3, placing the blackened copper foil 1 into a metal plating solution for surface electroplating treatment, so as to electroplate a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1, so as to obtain an electroplated copper foil; In this embodiment, the 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 .

[0058] In this embodiment, the silver-gray magnetic shielding alloy layer 2 is composed of three alloy layers of Ni-Cu, Ni-Mo, and Ni-Mo-Cr.

[0059] In this embodiment, the silver-gray magnetic shielding alloy layer 2 includes, from the inner layer to the outer layer, a second Ni—Cu alloy layer 26 , a Ni—Mo alloy layer 27 , and a Ni—Mo—Cr alloy layer 28 .

[0060] 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), 25g / L -30g / L boric acid, 100g / L -140g / L sodium citrate, 30g / L -50g / L sodium sulfate, bath temperature 45℃-65℃, bath pH 4.0±0.5, current density 4A / dm 2 -6A / dm 2 , electroplating time 1s-3s.

[0061] In this embodiment, in step S3, the thickness of the second Ni—Cu alloy layer 26 obtained by electroplating is 40 nm-50 nm, and the Ni content in the second Ni—Cu alloy layer 26 is 89 wt.%-96 wt.%.

[0062] In this embodiment, in step S3, the metal plating solution of the Ni-Mo alloy layer 27 includes 15g / L-20g / L Ni 2+ (nickel sulfate), 5g / L -8g / L MoO4 2- (sodium molybdate), 30g / L-50g / L ammonium acetate, 50g / L -100g / L sodium citrate, 20g / L -30g / L potassium sulfate, bath temperature 35℃-45℃, bath pH 3.0-3.6, current density 2A / dm 2 -4A / dm 2 , electroplating time 3s -5s.

[0063] In this embodiment, in step S3, the thickness of the Ni-Mo alloy layer 27 obtained by electroplating is 20 nm-25 nm, and the Ni content in the Ni-Mo alloy layer 27 is 93 wt.%-98 wt.%.

[0064] In this embodiment, in step S3, the metal plating solution of the Ni-Mo-Cr alloy layer 28 includes 2g / L-4g / L Ni 2+ (Nickel Sulfate), 15g / L -25g / L Cr 3+ (chromium sulfate), 4g / L -6g / L MoO4 2- (sodium molybdate), 20g / L -25g / L boric acid, 30g / L -50g / L sodium phosphate, 20g / L -30g / L sodium sulfate, bath temperature 20℃-40℃, bath pH 2.0±0.5, current density 1.0A / dm 2 -1.5A / dm 2 , electroplating time 4s -6s.

[0065] In this embodiment, in step S3, the thickness of the Ni—Mo—Cr alloy layer 28 obtained by electroplating is 10 nm-20 nm, and the Ni content in the Ni—Mo—Cr alloy layer 28 is 63 wt.%-76 wt.%.

[0066] S4, performing anti-oxidation treatment on the electroplated copper foil to form an anti-oxidation protective film 3 on the surface of the copper foil to obtain a silver-gray electromagnetic shielding copper foil.

[0067] In this embodiment, the anti-oxidation treatment is specifically to immerse in a tannic acid solution with a concentration of 3.0 wt.% for 30s-60s, and then blow dry with hot air.

[0068] The silver-gray electromagnetic shielding copper foil prepared by the above preparation method has a uniform silver-gray surface on both sides, the color system of the silver-gray surface CIE Lab is L: 76-84, a: 2.3-3.6, b: 5.5-7.5, the PIM value is (-150) - (-90) dBm, and has a good shielding effect.

[0069] 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, and the color system CIE Lab of the 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.

[0070] It should be noted that, in order to further verify the effect of the present invention, the present invention also provides the following comparative examples for corresponding comparison and explanation.

[0071] Comparative Example 1 Comparative Example 1 provides a method for manufacturing a 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 of Example 1, in which the blackened copper foil 1 is placed in a metal plating solution for surface electroplating treatment to electroplate a silver-gray magnetic shielding alloy layer 2 on the surface of the blackened copper foil 1 to obtain an electroplated copper foil; The electromagnetic shielding copper foil prepared by the preparation method provided in Comparative Example 1 has a uniform dark brown-red surface, a surface color system CIE Lab of L: 45-53, a: 9-17, b: 2-6, and a PIM value of (-60) - (-30) dBm.

[0072] Comparative Example 2 Comparative Example 2 provides a method for manufacturing a 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 immersing the treated copper foil in the blackening treatment liquid for blackening treatment in Step S2 of Example 1 to obtain the blackened copper foil 1; 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 the silver-gray magnetic shielding alloy layer 2. The color of the silver-gray surface is CIE Lab L: 81-90, a: 1.3-3.8, b: 6.0-7.5, and the PIM value is (-100) - (-30) dBm.

[0073] Comparative Example 3 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: in Comparative Example 3, 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; 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 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.

[0074] 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 a beautiful silver-gray color. The copper foil surface color CIE Lab was compared with the silver-gray electromagnetic shielding copper foil obtained in Example 1, and the L, a, and b values ​​were quite different, and its electromagnetic shielding performance was also relatively poor; compared with Example 2, Comparative Example 2 did not perform step S2 blackening treatment, and the prepared silver-gray electromagnetic shielding copper foil had higher brightness, the L value in the copper foil surface color CIE Lab increased, and the a and b values ​​decreased, the bonding force between the silver-gray magnetic shielding alloy layer 2 and the copper foil substrate became worse, 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 the outer layer was not electroplated with a Cr-containing nickel-based alloy layer. The prepared silver-gray electromagnetic shielding copper foil had higher brightness, and its silver-gray surface color CIE Lab could not meet the requirements, and the electromagnetic shielding performance was poor.

[0075] In summary, the silver-gray electromagnetic shielding copper foil prepared by the manufacturing method provided by the present invention has a unique silver-gray appearance on one side or both sides, and the color system CIE Lab of the silver-gray surface is L: 65-85, a: 0.5-4.0, b: 4-10. At the same time, its passive intermodulation performance is good, and the passive intermodulation PIM value is (-150) - (-70) dBm. It has good shielding performance and meets the requirements of the optical recognition and positioning system of the automated assembly line for its appearance and the electromagnetic shielding performance of electronic equipment.

[0076] 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 in 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. providing a copper foil to be treated, and sequentially performing a surface degreasing process and an acid solution cleaning process on the copper foil to be treated to obtain a treated copper foil; S2, providing a blackening treatment liquid, and immersing the treated copper foil in the blackening treatment liquid for blackening treatment to obtain a blackened copper foil; S3, placing the blackened copper foil in a metal plating solution for surface electroplating treatment, so as to electroplate a silver-gray magnetic shielding alloy layer on the surface of the blackened copper foil to obtain an electroplated copper foil; S4. Performing an anti-oxidation treatment on the electroplated copper foil to form a protective film on the surface of the electroplated copper foil to obtain a silver-gray electromagnetic shielding copper foil.

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

3. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that: In the step S2, the blackening treatment liquid includes 5g / L-60g / L copper salt, 40g / L-200g / L sulfuric acid, and 2g / L-10g / L blackening treatment additives, and the blackening treatment additives are two or three of hydrogen peroxide, acetic acid, disodium ethylenediaminetetraacetate, triethanolamine, tetrahydroxypropylethylenediamine, N-methyldiethanolamine, and sodium silicate. In the step S2, the temperature of the blackening treatment liquid is 35°C-60°C and the time is 3s-15s.

4. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that: The step S2 may also be: immersing the treated copper foil in the blackening treatment solution, taking one or both sides of the treated copper foil as the anode side, placing a DSA anode directly opposite and parallel to the anode side of the treated copper foil, applying current to the anode side and the cathode plate for electrochemical blackening treatment, and the current density of the electrochemical blackening treatment is 0.1A / dm 2 -0.5A / dm 2 .

5. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that: In step S3, the silver-gray magnetic shielding alloy layer is composed of at least two nickel-based metal / alloy layers of Ni, Ni-Cu, Ni-Cr, Ni-Mo, Ni-P, Ni-P-Cr, and Ni-Mo-Cr.

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

7. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 5, characterized in that: In the 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.%.

8. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that: In step S3, the plating solution temperature is 20°C-65°C, the plating solution pH is 2.0-4.5, and the current density is 0.2A / dm 2 -6A / dm 2 , electroplating time 1s-15s.

9. The method for manufacturing the silver-gray electromagnetic shielding copper foil according to claim 1, characterized in that: The step S4 is specifically as follows: The surface of the electroplated copper foil is immersed in, sprayed with, or brushed with an organic anti-oxidation solution, and then a protective film is formed on the surface of the electroplated copper foil by heating or air drying. 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.%.

10. A silver-gray electromagnetic shielding copper foil, characterized in that: The silver-gray electromagnetic shielding copper foil is prepared by the manufacturing method of the silver-gray electromagnetic shielding copper foil as described in any one of claims 1 to 9. One or both sides of the silver-gray electromagnetic shielding copper foil have a silver-gray appearance, and the color system CIE Lab of the 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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