Metal composite foil for electromagnetic shielding and preparation method and continuous preparation device thereof

Abstract

The invention discloses a metal composite foil for electromagnetic shielding and a preparation method and a continuous preparation device thereof, and relates to the technical field of electromagnetic shielding material preparation, the metal composite foil structurally comprises a copper foil substrate layer, and the upper surface and the lower surface of the copper foil substrate layer are respectively deposited with ferro-nickel alloy plating layers with the same thickness. The flexible electromagnetic shielding coating has flexibility and can have a good shielding effect on an electromagnetic field in a broadband electromagnetic range, the performance is superior to that of permalloy, and the surface of the coating is uniform, bright, coherent and dense. The formula composition of the plating solution adopts a foamless brightener, is suitable for continuous electroplating, and avoids the defects of black spots, dark fringes and the like which are easy to appear on a plating layer due to the adoption of a foamless additive. Moreover, according to the continuous preparation device disclosed by the invention, through a simple structural design, a post-treatment process and an electroplating process of the electroplated metal composite foil are combined in one system, and the space is saved by adopting a placement structure that a multi-plate anode foil strip and a multi-plate cathode foil strip are alternately arranged at intervals. And through the reasonable design of the flowing electroplating bath, stable circulation of the electroplating solution is ensured, and the stability of the metal composite foil coil product is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic shielding material preparation, and in particular to a metal composite foil for electromagnetic shielding, a preparation method thereof and a continuous preparation device. Background Art

[0002] With the advancement of technology, the integration of components in electronic products and the frequency of communication waves are constantly increasing. The combination of the two has led to increasingly serious electromagnetic interference in electronic products, and has put forward higher requirements on the quality and quantity of electromagnetic shielding films.

[0003] At present, for low-frequency electromagnetic waves, high magnetic permeability materials are needed, such as soft magnetic alloys (pure iron, silicon steel, Permalloy), etc.; for high-frequency electromagnetic waves, high-conductivity metal conductors are needed, such as silver, copper, etc. The Cu-FeNi alloy has a composite structure of "high conductivity (Cu) + high magnetic permeability (FeNi)", which broadens the frequency range of electromagnetic shielding and has good shielding effectiveness at both low and high frequencies. Depending on the application scenario, the requirements for electromagnetic shielding nickel-iron-copper metal composite foil are different, and there are also different requirements for the thickness of the nickel-iron alloy coating and the nickel-iron composition ratio.

[0004] The application announcement number is CN 103898574 A Chinese patent document discloses an electroplated Fe-Ni alloy magnetic shielding material and a preparation method thereof, wherein the electroplated Fe-Ni alloy magnetic shielding material comprises a composite shielding film material of several Cu films / or Ni films and several Fe-Ni alloy coatings, wherein the nickel content in the Fe-Ni alloy coating is 50-85%; the preparation method comprises: depositing a Cu film / or a Ni film on an aluminum alloy substrate; placing the aluminum alloy substrate in an electroplating solution, and electroplating a Fe-Ni alloy coating on the Cu film / or the Ni film, wherein the cathode is a 2024 aluminum alloy, and the anode is a nickel-iron alloy, and the composition content of the electroplating solution is: 60-200 g / L of nickel sulfate, 20 g / L of ferrous sulfate, 30 g / L of sodium chloride, 40 g / L of boric acid, 20 g / L of sodium citrate, 3 g / L of saccharin, 0.3 g / L of sodium benzene sulfinate, and 0.1 g / L of sodium dodecylbenzene sulfonate, and the pH value of the electroplating solution is controlled to be 3.2-3.8.

[0005] The composite shielding structure of the Fe-Ni alloy magnetic shielding material disclosed in the technical solution has high saturation magnetization, low residual magnetization and coercive force, and has a certain magnetic shielding effect in low-frequency magnetic field and static magnetic field. However, the shielding effect is not good under high-frequency electromagnetic, which is speculated to be related to the use of aluminum, which has a lower conductivity than copper, as the base material. At the same time, the electroplating contains saccharin and sodium dodecylbenzene sulfonate. These two chemical reagents will produce foam during the electroplating process, which is not suitable for the continuous preparation of Fe-Ni alloy foil, and affects the appearance of the electroplating layer to a certain extent, and even produces defects such as black spots and dark lines.

[0006] In summary, how to develop a shielding material with good electromagnetic shielding performance in a wide range, optimize its composition structure, plating solution formula composition, and its continuous preparation device are problems that technical personnel in this field need to solve. Summary of the invention

[0007] One of the purposes of the present invention is to provide a metal composite foil for electromagnetic shielding, which can shield electromagnetic waves in a wide frequency range.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solution: a metal composite foil for electromagnetic shielding, comprising a copper foil base layer, wherein nickel-iron alloy coatings of equal thickness are deposited on the upper and lower surfaces of the copper foil base layer.

[0009] Preferably, the iron content in the nickel-iron alloy coating is 15-25 wt%, and the balance is nickel; the thickness of the copper foil base layer is 10-20 um; and the thickness of the nickel-iron alloy coating is 10-40 um.

[0010] More preferably, the electromagnetic shielding frequency range of the metal composite foil for electromagnetic shielding is 10K-200KHz, and the shielding effectiveness range is 10-80dB.

[0011] In addition, the present invention also provides a method for preparing the above-mentioned metal composite foil for electromagnetic shielding, which includes the following steps: using copper foil as the cathode, and using a nickel plate and an iron plate combined in a certain proportion as the anode, depositing a nickel-iron alloy coating on both sides of the copper foil by electroplating, and then obtaining the metal composite foil for electromagnetic shielding by post-processing.

[0012] Preferably, the electroplating solution used in the electroplating process uses water as a solvent, and the ingredients include: 100-200 g / L nickel sulfate hexahydrate, 15-40 g / L ferrous sulfate heptahydrate, 30-60 g / L boric acid, 20-40 g / L nickel chloride hexahydrate, 20-50 g / L sodium chloride, 15-30 g / L trisodium citrate, and 1-10 g / L 1,3,6-naphthalene trisulfonic acid. Among them, nickel sulfate hexahydrate and ferrous sulfate heptahydrate are the main electroplating salts, trisodium citrate is a metal complexing agent, and 1,3,6-naphthalene trisulfonic acid is a non-foaming brightener.

[0013] More preferably, the pH value of the electroplating solution is 3-4.5; the surface area ratio of the anode to the cathode is 1:1-4:1, and in the anode, the surface areas of nickel and iron are 8:1-10:1; the copper foil is selected from electrolytic copper foil or rolled copper foil; the purity of the copper foil is >99%; and the thickness of the copper foil is 5-30um.

[0014] More preferably, the electroplating process is carried out by a constant current rectifier at 1.5-3.0 A / dm 2carried out at a current density of .

[0015] More preferably, the copper foil is pre-treated before use, and the pre-treatment includes pickling and cleaning; the post-treatment includes cleaning, hot air drying, and vacuum annealing.

[0016] Among them, the pickling liquid is 5%-10% sulfuric acid; the cleaning water is pure water; the hot air temperature of the hot air drying is 50-60°C; during the vacuum annealing process, the vacuum degree range is <-0.95MPa, and the annealing temperature range is 500-650°C.

[0017] In addition, the present invention also provides a continuous preparation device for the above-mentioned method of preparing the metal composite foil for electromagnetic shielding, comprising a pre-treatment device, a flow electroplating tank, a post-treatment device and a copper foil traction mechanism; the copper foil traction mechanism is used to pull the copper foil through the pre-treatment device, the flow electroplating tank, and the post-treatment device in sequence; a plurality of anode plates are installed in parallel and at intervals in the flow electroplating tank, and the anode plates are composed of a nickel plate and an iron plate. When the copper foil enters the flow electroplating tank, it passes through the gap between two adjacent anode plates one by one in an S-shaped route; the pre-treatment device comprises a pickling tank for removing the copper oxide layer on the surface of the copper foil and a cleaning tank for removing the pickling solution remaining on the surface of the copper foil after pickling; the post-treatment device comprises a water spray component for removing the plating solution remaining on the surface of the metal foil after electroplating and an air drying component for blowing the metal foil after electroplating.

[0018] Preferably, the copper foil traction mechanism includes an unwinding component, a conductive component, a traction component, a tension adjustment device and a winding component. The unwinding component is used to release the rolled copper foil. The conductive component is in close contact with the copper foil to apply current to the copper foil. The traction component is used to pull the copper foil to avoid folding of the copper foil. The winding component is driven by a motor to achieve winding of the electroplated metal foil and drive the copper foil to move.

[0019] More preferably, the flow electroplating tank includes an electroplating tank and an overflow tank, the electroplating solution continuously enters the bottom of the electroplating tank and enters the overflow tank through overflow at the top, and the electrolyte in the overflow tank is re-sent into the electroplating tank through a recovery mechanism.

[0020] More preferably, the anode plate can be removably installed in the slots on the inner walls on the left and right sides of the electroplating tank, and the lower part of the anode plate extends into the electrolyte, and a plurality of traction components are arranged at intervals on the top and the inner bottom of the electroplating tank, and the copper foil passes through the spacing areas of adjacent anode plates in sequence under the traction of the plurality of traction components so that the copper foil and the anode plate are alternately arranged in the electroplating tank.

[0021] Compared with the prior art, the metal composite foil for electromagnetic shielding of the present invention is flexible and can have a good shielding effect on electromagnetic fields in a wide frequency electromagnetic range, is superior to Permalloy 1J85 in performance, and has a uniform, bright, continuous and dense coating surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the metal composite foil for electromagnetic shielding of the present invention; Figure 2 It is a partial structural schematic diagram of the continuous preparation device in Example 1; Figure 3 It is a partial structural schematic diagram of the continuous preparation device in Example 1; Figure 4 It is a schematic diagram of the structure of the flow electroplating tank in Example 1; Figure 5 Schematic diagram of the structure of the anode plate in Example 1; Figure 6 It is a schematic diagram of the structure of the electroplating tank and the overflow tank in Example 1; Figure 7 This is a schematic diagram of the surface photograph of the metal composite foil for electromagnetic shielding prepared in Example 1; Figure 8 This is a schematic diagram of the surface photograph of the metal composite foil for electromagnetic shielding prepared in Comparative Example 1; Fig. 9 The EDS data results of measuring the iron and nickel content on the surface of the nickel-iron alloy composite copper foil prepared in Example 1; Fig.10 This is a SEM image of the surface of the metal composite foil prepared in Example 1; Fig.11 for Fig.10 Schematic diagram of EDS surface element scanning image of the area shown; Fig.12 for Fig.11 The schematic diagram of EDS surface element scanning results shown; Fig.13 This is a cross-sectional SEM image of the metal composite foil sample prepared in Example 1 adhered to a conductive tape; Fig.14 for Fig.13 Schematic diagram of EDS surface element scanning image of the area shown; Fig.15 for Fig.14 The schematic diagram of EDS surface element scanning results shown; Fig.16 Schematic diagram of the relationship between different current densities and the iron content of the coating in the embodiment; Fig.17 It is a schematic diagram of the results of the electromagnetic shielding energy efficiency test in the embodiment.

[0023] In the figure: 1——Metal composite foil 2——Anode plate 3——Conductive component 4——Traction component 5——Electroplating tank 6——Overflow tank 7——Liquid inlet pipe 8——Liquid outlet of overflow tank 9——Water spraying part 10——Cleaning liquid collection tank 11——Cleaning liquid outlet 12——Air drying parts 13——Tension adjustment component 14——Rewinding component 15——Cleaning tank 16——Pickling tank 17——Liquid storage tank 18——Filter 19——Liquid pump 20——Copper foil 101——Copper foil base layer 102——Nickel-iron alloy coating 103——Unwinding parts 501——Electroplating tank inlet valve 502——Electroplating tank outlet valve 503——Card slot 701——Liquid dispensing pipe outlet 702——Liquid inlet pipe main pipe 1501——Cleaning tank liquid inlet 1502——Cleaning tank liquid outlet 1601——liquid inlet of pickling tank 1602——liquid outlet of pickling tank. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0025] The following embodiments and comparative examples are all based on a continuous preparation device for metal composite foil for electromagnetic shielding. The structure of the device is as follows: Figure 2-6 As shown, it specifically includes a pre-treatment device, a flow electroplating tank, a post-treatment device and a copper foil pulling mechanism. Among them, the copper foil pulling mechanism is used to pull the copper foil 20 through the pre-treatment device, the flow electroplating tank, and the post-treatment device in sequence; a plurality of anode plates 2 are installed in parallel and at intervals in the flow electroplating tank, and the anode plates 2 are composed of a nickel plate and an iron plate. When the copper foil 20 enters the flow electroplating tank, it passes through the intervals between two adjacent anode plates 2 one by one in an S-shaped route; the pre-treatment device includes a pickling tank 16 for removing the copper oxide layer on the surface of the copper foil 20 and a cleaning tank 15 for removing the pickling solution remaining on the surface of the copper foil 20 after pickling; the post-treatment device includes a water spraying component 9 for removing the residual plating solution on the surface of the metal foil after electroplating and an air drying component 12 for blowing the metal foil after electroplating.

[0026] In the above structure, the copper foil pulling mechanism includes an unwinding component 103, a conductive component 3, a pulling component 4, a tension adjusting device 13 and a winding component 14. The unwinding component 103 is used to release the rolled copper foil 20. The conductive component 3 is in close contact with the copper foil 20 to apply current to the copper foil 20. The pulling component 4 is used to pull the copper foil 20 to avoid folding of the copper foil 20. The winding component 14 is driven by a motor to realize the winding of the electroplated metal foil and drive the copper foil 20 to move.

[0027] The flow electroplating tank includes an electroplating tank 5 and an overflow tank 6. The electroplating solution continuously enters the bottom of the electroplating tank 5 and flows into the overflow tank 6 at the top by overflow. The electrolyte in the overflow tank 6 is re-sent into the electroplating tank 5 through a recovery mechanism. Specifically, Figure 4 As shown, a liquid inlet pipe 7 is provided at the bottom of the electroplating tank 5, and a plurality of liquid distribution pipe openings 701 are distributed on the body of the liquid inlet pipe 7. The liquid inlet pipe 7 is connected to the filter 18 through the liquid inlet pipe main pipe 702, and the filter 18 is connected to the liquid pump 19, and the liquid pump 19 is connected to the liquid storage tank 17. One end of the liquid storage tank 17 is connected to the overflow tank 6. A plating tank liquid inlet valve 501 is provided between the liquid inlet pipe 7 and the filter 18, and a plating tank liquid outlet valve 502 is provided between the overflow tank 6 and the liquid storage tank 17. The overflow tank 6 is arranged close to the plating tank 6, and one side of the plating tank 5 is higher than the overflow tank 6 by 5cm-10cm, and a notch is provided on the upper edge of the side of the plating tank 5 to allow the plating solution to overflow into the overflow tank 6. The reasonable design of the flow plating tank ensures that the plating solution can circulate stably, which is beneficial to the stability of the metal composite foil roll product.

[0028] In addition, the anode plate 2 can be removably installed in the slot 503 on the inner wall of the left and right sides of the electroplating tank 5, and the lower part of the anode plate 2 extends into the electrolyte, and a plurality of traction components 4 are arranged at intervals above the electroplating tank 5 and on the inner bottom of the electroplating tank 5. The copper foil 20 passes through the spacing area of ​​adjacent anode plates 2 in sequence under the traction of the plurality of traction components 4 so that the copper foil 20 and the anode plate 2 are arranged alternately in the electroplating tank 5. The use of a structure in which multiple anodes and cathode copper foil strips are placed alternately saves space to the greatest extent. Those skilled in the art should know that the structure of the anode plate 2 can be directly made of nickel-iron alloy material, or the iron plate and the nickel plate can be directly combined together to form the anode plate 2 under the premise of cost saving, wherein the surface area of ​​nickel and iron is 8:1~10:1, such as Figure 5 As shown, the iron plate and the nickel plate are wrapped with insulating plates on all sides, and the top is connected to the conductive parts through a wire or a metal conductive sheet. Then the anode plate 2 is inserted into the slot 503. The insulating plate can ensure that the anode plate 2 and the electroplating tank 5 are insulated to avoid affecting the electroplating process. After being inserted into the slot 503, the anode plate 2 can extend into the electroplating solution and keep its top above the electroplating tank 5. At this time, the front and back surfaces of the anode plate 2 can contact the electroplating solution.

[0029] In the device, the current is set to 100 A. When electroplating 10 um thickness, the pulling speed of the copper foil 20 is: 2 m / min. Example

[0030] A method for preparing a metal composite foil for electromagnetic shielding, comprising the following steps: using a copper foil 20 as a cathode, and using a nickel plate and an iron plate in a certain ratio as an anode plate 2 as an anode, wherein the distance between the anode and the cathode is 10 mm, and the copper foil 20 is pulled by a pulling mechanism to pass through a pre-treatment device, a flow electroplating tank, and a post-treatment device in sequence. When passing through the electroplating tank 5, both sides of the copper foil 20 are simultaneously electroplated with a nickel-iron alloy coating, and then washed, dried, and vacuum annealed in sequence to obtain a nickel-iron alloy composite copper foil (structure as shown in FIG. Figure 1 As shown in Figure 1), that is, metal composite foil for electromagnetic shielding. The specific process steps are as follows: S1: In the preparation stage, the copper foil 20 is pulled from the unwinding part 103 to the winding part 14 through the traction part 4, the plating solution preheated to the set temperature is injected into the flow plating tank, the inlet flow rate of the plating solution in the plating tank 5 is adjusted to the set value, the motor of the winding part 14 is turned on, and the moving speed of the copper foil 20 is adjusted to the set value.

[0031] S2: electroplating stage: a set current value is transmitted to the current loop composed of the copper foil 20 and the anode plate 2 through the conductive component 3, so that the thickness of the coating formed on the surface of the copper foil 20 immersed in the electroplating solution reaches a set value.

[0032] S3: Rewinding stage: After electroplating, the metal composite foil is washed with pure water and dried with hot air in sequence, and then rolled up by the rewinding component 14.

[0033] S4: Annealing stage: The rolled metal composite foil is sent to a vacuum annealing furnace for annealing to eliminate the stress of the metal electroplating layer and remove hydrogen in the coating.

[0034] In this embodiment, the thickness of the copper foil 20 is 15um. The electroplating solution used in the electroplating process uses water as a solvent, and its ingredients include: 200 g / L nickel sulfate hexahydrate, 40 g / L ferrous sulfate heptahydrate, 60 g / L boric acid, 40 g / L nickel chloride hexahydrate, 30 g / L sodium chloride, 30 g / L trisodium citrate, and 1 g / L 1,3,6 naphthalene trisulfonic acid. Among them, nickel sulfate hexahydrate and ferrous sulfate heptahydrate are the main salts for electroplating, trisodium citrate is a metal complexing agent, and 1,3,6 naphthalene trisulfonic acid is a non-foaming brightener. The pH value of the electroplating solution is 4.1.

[0035] During the electroplating process, the surface area ratio of the anode to the cathode is 1:1, and the surface area ratio of the nickel plate to the iron plate in the anode is 8:1. A constant current rectifier is used at 2A / dm 2The electroplating was carried out at a current density of 1000 nm and a copper foil moving rate of 1 m / min, with an upper liquid flow rate of 50 L / min.

[0036] The pickling process uses 5wt% dilute sulfuric acid, and the cleaning process uses deionized water. The technical process conditions of vacuum annealing are specifically 2 hours at a vacuum temperature of -1MPa and 550°C.

[0037] In the nickel-iron alloy composite copper foil prepared in this embodiment, the nickel-iron alloy coating is uniformly deposited on both sides of the copper foil 20, and the coating thickness on one side is 10 μm.

[0038] Figure 7 This is a photo of the nickel-iron alloy composite copper foil prepared in this example, and the surface of the coating is bright.

[0039] Fig. 9 The table shown is the EDS measurement data of the iron-nickel content on the surface of the nickel-iron alloy composite copper foil prepared in this example. The results show that the iron content ranges from 15% to 20%. Example

[0040] The only difference between this embodiment and embodiment 1 is the movement rate of the copper foil during the electroplating process. Specifically, the movement rate of the copper foil during the electroplating process in this embodiment is 1.5 m / min, the iron content of the obtained metal composite foil is 18-22%, and the coating thickness on one side is 7 μm.

[0041] The metal composite foil prepared in this embodiment was scanned by a scanning electron microscope, and the obtained SEM image is as follows: Fig.10 As shown. By performing EDS surface element scanning on this area, the results are as follows Fig.11 and Fig.12 As shown, through analysis, it can be seen that the Fe / Ni element content ratio is 19:81. From the EDS surface scanning element distribution map, it can be seen that the two elements are evenly distributed on the copper base surface.

[0042] In addition, the metal composite foil sample prepared in this embodiment was directly adhered to the conductive tape for observation, and the cross-sectional SEM image obtained was as follows: Fig.13 As shown in the figure, since the nickel-iron alloy coating on the lower layer is blocked by the tape layer, only the upper nickel-iron alloy coating and the middle copper foil base layer are shown in the figure. Through measurement, it can be seen that the thickness of the upper nickel-iron alloy coating is approximately 7um, and the thickness of the middle copper foil base layer is approximately 15um. By performing EDS surface element scanning on this area, the results are as follows Fig.14 and Fig.15 As shown, it can be seen from the figure that the nickel and iron in the upper nickel-iron alloy coating are evenly distributed. Example

[0043] The difference between this embodiment and embodiment 1 is that the current density used is different. Specifically, the current density of this embodiment is 1A / dm 2 The iron content of the obtained metal composite foil is 25~30%, and the coating thickness on one side is 5μm. Example

[0044] The difference between this embodiment and embodiment 1 is that the current density used is different. Specifically, the current density of this embodiment is 0.5A / dm 2 The iron content of the obtained metal composite foil is 30~35%, and the coating thickness on one side is 2.5μm.

[0045] The results of the above embodiments are statistically analyzed to obtain the following: Fig.16 The relationship curve between current density and iron content of the coating is shown.

[0046] The only difference between this comparative example and Example 1 is that the brightener 1,3,6-naphthalenetrisulfonic acid is not added to the electroplating solution. Figure 8 As shown, the surface of the coating is not bright, which is completely different from the surface condition of the metal composite foil prepared in Example 1.

[0047] The electromagnetic shielding efficiency of the metal composite foils prepared in the above-mentioned embodiments 1, 3 and 4 was tested. Fig.17 It can be seen from the table that under the electromagnetic frequency environment of 30KHz and 199KHz, the metal composite foils of Example 1, Example 3 and Example 3 all have good electromagnetic shielding efficiency. It can be seen that the metal composite foil for electromagnetic shielding prepared by the present invention can shield electromagnetic waves in a wide frequency range.

[0048] The metal composite foil prepared by the present invention has good flexibility, which is not only due to the fact that the thickness of the metal composite foil is strictly controlled within the range of 10-40um, which can meet the needs of electromagnetic shielding and prevent the composite foil from becoming too hard and brittle, but also due to the addition of 1,3,6-naphthalenetrisulfonic acid as a bubble-free brightener in the electroplating solution. This additive can avoid the generation of bubbles during the electroplating process, thereby ensuring the uniformity and density of the coating. The uniform coating helps to maintain the overall performance of the material, including flexibility. More importantly, the continuous preparation device can ensure that the copper foil is uniformly stressed during the electroplating process, avoiding local stress concentration that causes the material to become brittle. These enable the metal composite foil to produce better flexibility, thereby enabling it to meet the needs of various complex application scenarios.

[0049] In addition, the metal composite foil prepared by the present invention can have a good shielding effect on the electromagnetic field in a wide frequency electromagnetic range, and its performance is better than that of Permalloy 1J85. The surface of the coating is uniform, bright, coherent and dense. The plating solution formula uses a non-foaming brightener, which is suitable for continuous electroplating, avoiding the defects of black spots, dark lines and the like that are easy to appear in the coating due to the use of foaming additives. In addition, the continuous preparation device proposed by the present invention combines the cleaning and air-drying post-treatment process of the electroplated metal composite foil with the electroplating process in one device system through a simple structural design, and adopts a multi-plate anode and cathode foil strip alternately placed structure to save space to the greatest extent. And through the reasonable design of the flow electroplating tank, it is ensured that the plating solution can circulate stably, which is beneficial to the stability of the metal composite foil roll product.

[0050] In order to make it easier for ordinary technicians in the field to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and the above-mentioned embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

Claims

1. A metal composite foil for electromagnetic shielding, characterized in that: It comprises a copper foil base layer (101), wherein nickel-iron alloy coating layers (102) of equal thickness are deposited on the upper and lower surfaces of the copper foil base layer (101).

2. The metal composite foil for electromagnetic shielding according to claim 1, characterized in that: The iron content in the nickel-iron alloy coating (102) is 15-25 wt%, with the remainder being nickel; the thickness of the copper foil base layer (101) is 10-20 um; and the thickness of the nickel-iron alloy coating (102) is 10-40 um.

3. A method for preparing the metal composite foil for electromagnetic shielding according to claim 1 or 2, characterized in that: The following steps are involved: The copper foil is used as the cathode, and the nickel plate and the iron plate are combined in a certain proportion as the anode. The nickel-iron alloy coating is deposited on both sides of the copper foil by electroplating, and then the metal composite foil for electromagnetic shielding is obtained by post-processing.

4. The method for preparing the metal composite foil for electromagnetic shielding according to claim 3, characterized in that: The plating solution used in the electroplating process uses water as a solvent, and its ingredients include: 100~200 g / L of nickel sulfate hexahydrate, 15~40 g / L of ferrous sulfate heptahydrate, 30~60 g / L of boric acid, 20~40 g / L of nickel chloride hexahydrate, 20-50 g / L of sodium chloride, 15~30 g / L of trisodium citrate and 1~10 g / L of 1,3,6-naphthalenetrisulfonic acid.

5. The method for preparing the metal composite foil for electromagnetic shielding according to claim 3, characterized in that: The pH value of the electroplating solution is 3-4.5; the surface area ratio of the anode to the cathode is 1:1-4:1, and in the anode, the surface areas of nickel and iron are 8:1-10:1; the copper foil is selected from electrolytic copper foil or rolled copper foil; the purity of the copper foil is >99%; the thickness of the copper foil is 5-30um.

6. The method for preparing the metal composite foil for electromagnetic shielding according to claim 3, characterized in that: The electroplating process is carried out by a constant current rectifier at 1.5~3.0 A / dm 2 carried out at a current density of .

7. The method for preparing the metal composite foil for electromagnetic shielding according to claim 3, characterized in that: The copper foil is pre-treated before use, and the pre-treatment includes pickling and cleaning; the post-treatment includes cleaning, hot air drying, and vacuum annealing.

8. A continuous preparation device for the method for preparing the metal composite foil for electromagnetic shielding according to any one of claims 3 to 7, characterized in that: The invention comprises a pre-treatment device, a flow electroplating tank, a post-treatment device and a copper foil pulling mechanism; the copper foil pulling mechanism is used to pull the copper foil (20) through the pre-treatment device, the flow electroplating tank and the post-treatment device in sequence; a plurality of anode plates (2) are installed in parallel and at intervals in the flow electroplating tank, the anode plates (2) being composed of a nickel plate and an iron plate, and the copper foil (20) passes through the interval between two adjacent anode plates (2) one by one in an S-shaped route when entering the flow electroplating tank; the pre-treatment device comprises a pickling tank (16) for removing the copper oxide layer on the surface of the copper foil (20) and a cleaning tank (15) for removing the pickling liquid remaining on the surface of the copper foil (20) after pickling; the post-treatment device comprises a water spraying component (9) for removing the plating liquid remaining on the surface of the metal foil after electroplating and an air drying component (12) for blowing the metal foil after electroplating.

9. The continuous preparation device according to claim 8, characterized in that: The flow electroplating tank comprises an electroplating tank (5) and an overflow tank (6); electroplating solution continuously enters the bottom of the electroplating tank (5) and enters the overflow tank (6) at the top by overflow; the electrolyte in the overflow tank (6) is re-sent into the electroplating tank (5) through a recovery mechanism.

10. The continuous preparation device according to claim 9, characterized in that: The anode plate (2) is detachably mounted in the slots (503) on the inner walls of the left and right sides of the electroplating tank (5), and the lower part of the anode plate (2) extends into the electrolyte. A plurality of traction components (4) are arranged at intervals above the electroplating tank (5) and at the inner bottom of the electroplating tank (5). The copper foil (20) passes through the interval area of ​​adjacent anode plates (2) in sequence under the traction of the plurality of traction components (4), so that the copper foil (20) and the anode plate (2) are arranged alternately and at intervals in the electroplating tank (5).

Images