Copper-plated composite film and method for chemically plating copper on surface of copper-plated composite film

Abstract

The invention relates to a copper-plated composite film and a surface chemical copper plating method thereof, the copper-plated composite film comprises a base material, two surfaces of the base material are provided with copper-plated layers, the thickness of the single-surface copper-plated layer is 1 [mu] m, and the base material is a polymer of one or more than two of poly (p-phenylene terephthamide), poly (m-phenylene isophthamide) and polyoxadiazole. The adopted base material has good heat resistance, and a high vehicle speed can be adopted. And the binding force between the base material and the copper-plated layer is strong, and the copper-plated composite film is good in performance. According to the method, the coating uniformity during copper plating can be improved, and the yield of the copper-plated composite film is increased.

Description

Technical Field

[0001] The present invention relates to a copper-plated composite film and a method for electroless copper plating on its surface, belonging to the technical field of film material preparation. Background Art

[0002] In the traditional lithium-ion battery structure, copper foil is used as the negative current collector, resulting in high material costs. When a composite film current collector with copper plating on the surface of a polymer substrate is used to replace copper foil, the material cost can be significantly reduced, and the battery energy density can be increased.

[0003] Currently, the copper-plated composite films studied more often use PET, PP, and PI as substrates. All three different substrates have deficiencies, which limit the practical application of copper-plated composite films. The PET substrate has poor stability and is prone to reacting with the electrolyte, causing short circuits between the positive and negative electrodes; the PP substrate has insufficient bonding force with the copper coating, and gaps and copper powder shedding are likely to occur, affecting its performance; both PET and PP substrates have poor high-temperature resistance. The high-temperature resistance temperature is 100 °C, and the substrate is prone to thermal deformation, resulting in a low vehicle speed during copper plating. The PI substrate has better performance, with a high-temperature resistance temperature of 450 °C, but it is expensive and has a high cost.

[0004] When producing copper-plated composite films, a two-step method is generally used. First, a 10-20 nm substrate is deposited by vacuum magnetron sputtering, and then the copper plating layer is thickened to 1 μm by evaporation or electroplating. The difficulty in producing copper-plated composite films lies in the uneven thickness of the coating layer and the low yield rate. Summary of the Invention

[0005] One technical objective of the present invention is to provide a copper-plated composite film with excellent performance and appropriate cost. The specific solution is as follows:

[0006] A copper-plated composite film includes a substrate, with copper plating layers provided on both sides of the substrate. The thickness of the single-sided copper plating layer is 1 μm, and the substrate is one or more polymers selected from poly(p-phenyleneterephthalamide), poly(m-phenyleneterephthalamide), and polyoxadiazole.

[0007] Furthermore, the thickness of the substrate is 4 μm.

[0008] The substrate selected by the present invention has good high-temperature resistance. The high-temperature resistance temperature is between 450 and 500 °C. It is not prone to deformation during copper plating, and a relatively fast vehicle speed can be used. Moreover, the bonding force between the substrate and the copper coating is strong, and the performance is good. The cost of the selected substrate is significantly lower than that of the PI substrate, making it suitable for popularization.

[0009] Another technical objective of the present invention is to solve the problem of uneven thickness during copper plating of the substrate. The specific solution is a method for electroless copper plating on the surface of a copper-plated composite film, which includes the following steps: 1) First, the substrate is coated by magnetron sputtering to deposit a copper coating with a thickness of 0.04 - 0.08 μm on both sides of the substrate; 2) Then, through evaporation or electroplating, the thickness of the copper coating is increased to 1 μm.

[0010] Further, in step 1), after magnetron sputtering coating, the thickness of the copper coating is controlled within 0.05 - 0.1 μm.

[0011] Further, in step 1), during magnetron sputtering coating, a first detection point is set before coating the substrate, a second detection point is set after coating the first side of the substrate, and a third detection point is set after coating the second side of the substrate. A film thickness detector is set at each detection point, and the detection accuracy of the film thickness detector is 0.01 μm. The thickness of the coating on the first side is controlled according to the detection value of the second detection point and the detection value of the first detection point, and the thickness of the coating on the second side is controlled according to the detection value of the third detection point and the detection value of the second detection point.

[0012] Further, in step 1), during magnetron sputtering coating, the film thickness detector is slidably arranged along the width direction of the substrate and can reciprocally move and detect the film thickness of the substrate along the width direction of the substrate; a plurality of argon inlets are uniformly arranged along the width direction of the shell of the sputtering cathode, and each argon inlet is provided with an independent flow valve; when the film thickness detector moves to detect the film thickness of the substrate, the average film thickness within one stepping period is calculated, and the stepping period is obtained according to the width of the substrate and the number of argon inlets; the argon flow rate of a single argon inlet is controlled according to the average film thickness.

[0013] Further, the moving speed of the film thickness detector is not less than 0.3 times the vehicle speed during magnetron sputtering coating.

[0014] In the prior art, a continuous coating machine is generally used to coat copper on the substrate. When using PET or PP substrates, the vehicle speed is generally below 10 m / min, and the production efficiency is low. When using a PI substrate with good heat resistance, the vehicle speed is above 20 m / min.

[0015] In the present invention, the substrate used also has good heat resistance and can adopt a higher vehicle speed. Moreover, the bonding strength between the substrate and the copper coating is strong, and the performance of the copper-coated composite film is good.

[0016] In addition, the method of the present invention can improve the coating uniformity during copper coating and increase the yield rate of the copper-coated composite film.

[0017] The copper-coated composite film of the present invention can be used for the composite current collector of power batteries and can also be used in the 3C and photovoltaic industries. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the magnetron sputtering coating device in Example 5.

[0019] Figure 2 It is a schematic diagram of the film thickness detector in Example 5. Specific implementation mode

[0020] The following combines specific examples to elaborate on the solution of this invention patent in detail. Example 1

[0021] The base material in this example is poly(p-phenyleneterephthalamide), with a base material thickness of 4 μm and a width of 1000 mm. The base material is copper-plated on a continuous coating equipment at a vehicle speed of 20 m / min. First, copper is plated on both sides at one time by vacuum magnetron sputtering to prime the surface of the base material, with a thickness of 10 - 200 nm; then the thickness of the copper plating layer on both sides is increased to 1 μm by electroplating, and finally a copper-plated composite film with a thickness of 6 μm is obtained. The chemical composition of the copper plating agent used in electroplating is: copper sulfate pentahydrate 160 g / L, sulfuric acid 100 g / L, brightener 5 g / L, stabilizer 4 g / L; the current density is 3 A / dm 2 . Example 2

[0022] The base material in this example is poly(m-phenyleneterephthalamide), and the rest of the process is the same as that in Example 1. Example 3

[0023] The base material in this example is polyoxadiazole, and the rest of the process is the same as that in Example 1. Example 4

[0024] The base material in this example is a mixture of poly(p-phenyleneterephthalamide) and poly(m-phenyleneterephthalamide) with a mass ratio of 1:1, and the rest of the process is the same as that in Example 1.

[0025] The adhesion of the copper-plated composite films prepared in Examples 1 - 4 was detected. The adhesion of the coating was tested using tape according to the standard GB / T 4677.7 - 1984 "Test method for adhesion of coatings on printed boards. Tape method", and no copper powder fell off.

[0026] In Example 1, when the coating uniformity is controlled within 1%, the yield is 93%. In the two-step copper plating process, the purpose of the first step of magnetron sputtering copper plating is for bottoming, generating a conductive layer on the substrate surface to enable the second step of electroplating copper. After the final copper plating is completed, the thickness requirement of the composite film is controlled at 6 ± 0.06 μm. Generally, it is considered that the purpose of the first step of sputtering copper plating is to make the substrate conductive, and the requirement for coating uniformity is mainly reflected in the second step of electroplating copper. However, in actual control, the uniformity problem during the first step of copper plating will further affect the uniformity of the second step of copper plating. That is, when the coating thickness during magnetron sputtering copper plating is uneven, it will cause uneven conductivity of the substrate, and during electroplating copper, the current density has a great influence on the copper plating speed. Especially under the condition of a relatively fast vehicle speed, the problem of coating uniformity is more prominent. Example 5

[0027] Based on Example 1, the copper plating process was improved, such as Figure 1 , specifically, a first detection point 1 is set before coating in the vacuum magnetron sputtering device of the continuous coating equipment, a second detection point 3 is set after coating on the first side of the substrate 2, and a third detection point 5 is set after coating on the second side of the substrate 4. A film thickness detector 6 is set at each detection point, and the detection accuracy of the film thickness detector is 0.01 μm. The thickness of the coating on the first side is controlled according to the detection value of the second detection point and the detection value of the first detection point, and the thickness of the coating on the second side is controlled according to the detection value of the third detection point and the detection value of the second detection point. The thickness control of magnetron sputtering coating can be achieved by adjusting the power of the sputtering cathode 7.

[0028] In addition, such as Figure 2 , the film thickness detector 6 is slidably arranged along the width direction of the substrate 8 and can reciprocally move and detect the film thickness of the substrate along the width direction of the substrate; a plurality of argon inlets 9 are uniformly arranged along the width direction of the shell of the sputtering cathode 7, and each argon inlet is provided with an independent flow valve; when the film thickness detector moves and detects the film thickness of the substrate, the average film thickness value within a stepping cycle is calculated, and the stepping cycle is obtained according to the width of the substrate and the number of argon inlets; the argon flow rate of a single argon inlet is controlled according to the average film thickness value. The moving speed of the film thickness detector is not less than 0.5 times the vehicle speed during magnetron sputtering coating.

[0029] For example, when the vehicle speed is 20 m / min and the substrate width is 1000 mm, the number of argon gas inlets is 3, the moving speed of the film thickness detector is 0.25 m / s, and the moving step period is set to 1 s. According to this setting, the substrate is divided into 4 control regions in the width direction. The film thickness detector passes through one detection region every 1 s, the reading frequency is set to 4 times / s, one step period corresponds to one detection region, the average film thickness of 4 readings in one detection region is calculated, and the fluctuation range of the average film thickness of each region is controlled within ±0.02 μm. Through improvement, when the coating uniformity of the copper-plated composite film is controlled within 1%, the yield rate can be increased to 95%.

Claims

1. A copper-plated composite film, characterized in that: The invention comprises a substrate, wherein copper plating layers are arranged on both sides of the substrate, and the thickness of the copper plating layer on one side is 1 micrometer. The substrate is one or more polymers selected from poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide) and polyoxadiazole.

2. The copper-plated composite film according to claim 1, characterized in that: The substrate thickness was 4 μm.

3. The method for chemical copper plating on the surface of a copper-plated composite film according to claim 1 or 2, characterized in that: The following steps are involved: 1) The substrate is first coated by magnetron sputtering, and a 0.01-0.2μm copper layer is plated on both sides of the substrate; 2) Then increase the thickness of the copper plating layer to 1μm through evaporation or water electroplating.

4. The method for chemical copper plating on the surface of a copper-plated composite film according to claim 3, characterized in that: In step 1), after magnetron sputtering coating, the thickness of the copper coating is controlled to be 0.04-0.08 μm.

5. The method for chemical copper plating on the surface of a copper-plated composite film according to claim 4, characterized in that: In step 1), during magnetron sputtering coating, a first detection point is set before coating the substrate, a second detection point is set after coating the first side of the substrate, and a third detection point is set after coating the second side of the substrate. A film thickness detector is set at each detection point, and the detection accuracy of the film thickness detector is 0.01 μm. The thickness of the coating on the first side is controlled according to the detection value of the second detection point and the detection value of the first detection point, and the thickness of the coating on the second side is controlled according to the detection value of the third detection point and the detection value of the second detection point.

6. The method for chemical copper plating on the surface of a copper-plated composite film according to claim 5, characterized in that: In step 1), during magnetron sputtering coating, the film thickness detector is slidably arranged along the width direction of the substrate, and can reciprocate and detect the film thickness of the substrate along the width direction of the substrate; the shell of the sputtering cathode is evenly provided with multiple argon gas inlets along the width direction, and each argon gas inlet is provided with an independent flow valve; when the film thickness detector performs mobile detection of the film thickness of the substrate, the average film thickness within a step cycle is calculated, and the step cycle is obtained according to the width of the substrate and the number of argon gas inlets; the argon gas flow rate of a single argon gas inlet is controlled according to the average film thickness.

7. The method for chemical copper plating on the surface of a copper-plated composite film according to claim 6, characterized in that: The moving speed of the film thickness detector shall not be less than 0.3 times the vehicle speed during magnetron sputtering coating.

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