A method for reducing the thickness of a copper material

Abstract

The present application belongs to the field of copper metal materials, and particularly relates to a copper material thinning processing method. The method comprises the following steps: 1) obtaining initial critical deformation data and standard pass sequence variation coefficient data of the copper material to be processed; 2) calculating a thinning drawing standard pass sequence coefficient based on a target thinning deformation; 3) calculating a processing thinning deformation and controlling a single processing amount in the copper material thinning processing according to the calculation result; and 4) based on the calculation result of step 3), performing thinning processing on the copper material to be processed until the target thickness is reached. The processing method of the present application realizes effective copper material thinning processing, can realize effective processing and preparation of ultra-thin planar copper material, effectively retains the mechanical properties of the copper material, and is suitable for industrial processing, simple, efficient and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of copper metal materials, and particularly relates to a method for thinning copper materials. Background Technology

[0002] Copper is a very common and widely used metallic material with excellent thermal conductivity, electrical conductivity, electrochemical activity, and toughness, making it widely applicable in many fields. For example, in the field of electrode materials, its strong electrical conductivity and electrochemical activity make it a very important electrode material. Furthermore, it is used in the production of numerous devices such as electrical components, lamp holders, battery caps, buttons, seals, and connectors.

[0003] However, current processing methods for copper plates, sheets, and foils all have certain drawbacks. This is especially true for the preparation of ultra-thin copper foil, where each method has its limitations. For example, copper foil produced by the common electrolytic method has a very small maximum thickness, approaching 0.004 mm, but it suffers from poor hardness, generally low tensile strength, and high cost. While rolled copper foil typically uses a more advanced double-rolling method, it can only effectively produce copper foil with a thickness of about 0.012 mm. When preparing even thinner copper foil, breakage and cracking are very likely to occur.

[0004] Therefore, developing a low-cost copper thinning process is of great significance for the industrial production of ultra-thin copper materials while ensuring their mechanical properties. Summary of the Invention

[0005] To address the challenges of effectively thinning planar copper materials using existing processes, which often suffer from high costs, poor performance, or limitations in the preparation of ultra-thin planar copper materials, this invention provides a copper material thinning processing method.

[0006] The purpose of this invention is:

[0007] I. Capable of processing and preparing ultra-thin planar copper materials;

[0008] Second, the preparation cost is relatively low;

[0009] Third, ensure that the produced copper material has good mechanical properties.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] A method for thinning copper materials,

[0012] The method includes:

[0013] 1) Obtain the initial critical deformation Def of the copper material to be processed. c Data and standard track sequence variation coefficient C;

[0014] 2) Based on the target thinning deformation amount Def t The standard pass sequence coefficient f for thinning and drawing is calculated using the following formula:

[0015]

[0016] In the formula: f is the standard sequence coefficient for thinning and drawing, satisfying f≥3, and has no unit; Def t The target thinning deformation, dimensionless; Def c , where C is the initial critical deformation, dimensionless; C is the standard track sequence variation coefficient, dimensionless.

[0017] 3) Calculate the thinning deformation Def in the nth processing step. n Based on the calculation results, the single processing amount during the copper material thinning process is controlled, and the thinning deformation amount Def in the nth processing is determined. n The calculation is performed using the following formula:

[0018]

[0019] In the formula: Def n This refers to the thinning deformation amount in the nth processing step, where n is a positive integer and has no unit. c F represents the initial critical deformation, which is dimensionless. n The processing order is defined by n, which is a positive integer with no unit; f is the standard pass order coefficient for thinning and drawing, which satisfies f≥3 and has no unit.

[0020] 4) Based on the calculation results of step 3), perform F on the copper material to be processed. n The thinning process is repeated until the target thickness is achieved. Except for the last thinning process, the deformation amount of each thinning process is controlled to meet the requirements of step 3) the deformation amount Def of the nth thinning process. n According to the calculation results, the copper material was subjected to low-temperature annealing after the first to the penultimate thinning process, and final annealing was carried out after the last thinning process to complete the copper material thinning process.

[0021] As a preferred option

[0022] Step 1) The standard track sequence variation coefficient C is calculated by the following formula:

[0023]

[0024] In the formula: C is the standard track sequence variation coefficient, which has no unit; Def cThis is the initial critical deformation, dimensionless; Def c ′ represents the critical deformation amount measured during the second critical deformation processing after the first critical deformation processing and low-temperature annealing treatment. It has no unit.

[0025] As a preferred option

[0026] The low-temperature annealing is performed at 120–150°C for 25–35 minutes.

[0027] As a preferred option

[0028] Step 4) The low-temperature annealing is performed at 120-150℃ for 25-35 minutes.

[0029] As a preferred option

[0030] Step 4) The final annealing is performed at 180-220℃ for 30-60 minutes.

[0031] As a preferred option

[0032] The method is used for processing plate-shaped, sheet-shaped, or foil-shaped copper materials.

[0033] The core of the technical solution of this invention lies in the reasonable control of the entire process of thinning copper material, the control of the microscopic morphological characteristics and macroscopic mechanical properties of copper material after each thinning process, and the method of this invention is applicable to the existing cold rolling and thinning process. Unless otherwise specified, this invention includes subsequent embodiments, and the actual "thinning process" is cold rolling and thinning.

[0034] Regarding the overall process control of thinning, the core of this invention lies in achieving near-critical processing of copper materials. Critical processing is a common and frequently used processing method in the field of metal processing. Compared with conventional non-critical processing methods (where the processing deformation is less than the critical deformation), critical processing methods enable the processing deformation to be much greater than the critical deformation of conventional copper materials, that is, 10-20% more than the critical deformation of conventional copper materials.

[0035] In conventional copper foil production, over-thinning rolling is often employed, with some processes resulting in a single-batch reduction in deformation (reduction rate) exceeding 50%. This is because, before the critical deformation amount, as the deformation increases, the copper grains continuously deform and accumulate dislocations. Approaching the critical deformation amount, the copper exhibits significant hardness and brittleness, making it prone to cracking and even fracture. However, with over-thinning rolling, the copper can easily recrystallize during annealing, refining the grains and significantly optimizing its mechanical properties. However, over-thinning rolling also has significant drawbacks. For example, when the copper thickness is too small, grain breakage leads to excessive dislocations, defects, and grain boundaries, causing a sharp increase in the cracking and fracture rate, making effective rolling difficult. For instance, when the copper thickness reaches approximately 10 μm, cracking becomes very easy.

[0036] This invention employs a unique continuous near-critical rolling method, combined with a single-sided annealing process. Specifically, the technical solution of this invention was inspired by the development of a thin-walled micro heat pipe fabrication process. In the development of micro heat pipes, the researchers of this invention adopted an inner wall heating and outer wall cooling method to achieve effective near-critical thinning processing. However, due to the unique characteristics of the tube material itself, there are certain differences between the actual conditions of the inner and outer walls during the core drawing process. Therefore, it is necessary to control the temperature simultaneously during the core drawing process. However, planar copper materials, such as plates, sheets, and foils, have a high degree of consistency on both sides during the rolling and pressing thinning process, which can simplify the process and be carried out entirely by cold rolling and other methods. Moreover, since planar copper materials are easier to process than tubular copper materials, this invention further modified and verified the original micro heat pipe Finite Element Analysis model to further refine the parameter control of planar materials, thereby forming a better parameter control model. A new Finite Element Analysis model was constructed and verified, mainly controlling the deformation of a single pressing thinning, i.e., the aforementioned deformation amount Def of the nth processing thinning. The following complete model is formed:

[0037]

[0038] In the formula: Def n This refers to the thinning deformation amount in the nth processing step, where n is a positive integer and has no unit. c F represents the initial critical deformation, which is dimensionless. n The processing order is given by n, which is a positive integer with no unit. t The target thinning deformation, dimensionless; Def c′ represents the critical deformation amount measured during the second critical deformation processing after the first critical deformation processing and low-temperature annealing treatment. It has no unit.

[0039] The formula for calculating the standard pass sequence coefficient f in the thinning drawing process is the simplified version after substitution. The specific formula and simplification are as follows:

[0040] The formula is: In the process of establishing the Finite Element Analysis model, the original model of the standard pass order coefficient f for thinning drawing was constructed and calculated using the following set of formulas obtained after finite element simulation analysis:

[0041] f = ceil(f′)

[0042]

[0043] Where floor is calculated using the floor function and ceil is calculated using the ceiling function. Let n be the amount of denaturation retained after the nth thinning treatment. In the above formula set, n is represented by a number, a, or f′, and the other symbols have the same meaning as in the previous formula.

[0044] Based on the above calculations, the result f is obtained. ′ When f is not an integer, and after validation using the Finite Element Analysis model, a certain bias is found. The bias increases with the increase of f (i.e., Def). t Increase or Def c After the reduction, the deviation of the f result calculated by the above formula set becomes larger. Therefore, based on the existing Finite Element Analysis model, specific experimental results, and the existing formula set, a fitting analysis is performed. Conventional mathematical processing is carried out in Origin and MATLAB analysis software to obtain the optimized approximate calculation formula for the standard pass order coefficient f of thinning and drawing, as described above: However, it should be noted that there are restrictions when substituting this approximate formula into the calculation, namely, it is necessary to ensure that f≥3 and Def t ≥0.352 = 35.2% is used to reduce deviation, and due to the limitations of this approximate calculation formula, this invention should be best applied to the target thinning deformation amount Def. t ≥0.5 (i.e., target thinning deformation Def) t ≥50% of planar copper materials are treated.

[0045] The above approximate calculation formula can more conveniently and quickly calculate the standard pass sequence coefficient f for thinning and drawing, and the effect of substituting it into the formula is the best when calculating the thinning deformation Def of the nth processing.

[0046] The machining amount is calculated using the thinning deformation Def obtained from the nth machining process. Under the control of the above parameters, effective near-critical deformation machining can be achieved, but this is not enough; single-sided low-temperature annealing is also required after each thinning process.

[0047] The single-sided low-temperature annealing process involves cooling one side with inert gas and heating the other side with contact heat transfer. Specifically, a ceramic heater is used to press one side of the flat copper material against the other side, while the other side remains air-cooled. During the single-sided low-temperature annealing process, the heated side of the copper material is kept at 120–150°C for 25–35 minutes, while the cooled side is kept at ≤60°C, creating a temperature difference. At this point, the heat treatment surface, under low-temperature annealing conditions, differs from the treatment method of the tube. In the thin-walling process of the micro heat pipe, preheating of the core head creates a temperature gradient before full-tube annealing to refine the inner wall grains and compress them, causing the grain breakage and refinement trend to extend towards the outer wall. Then, low-temperature annealing of the entire tube optimizes strength and toughness. However, for the planar copper material of this invention, the two sides are essentially the same, with no difference. In near-critical deformation processing, using a single-sided low-temperature annealing process allows the heated surface to achieve grain breakage and refinement through contact heat treatment, while the cooling surface, under continuous cooling, experiences compression and some degree of breakage, forming a "gradient grain size." This improves the strength and toughness of the copper material while eliminating residual stress, achieving effective control over the microstructure of the copper material and enabling repeated near-critical processing. However, the actual critical deformation during processing will change, requiring supplementary correction. This supplementary correction is achieved through the standard pass order coefficient f and the standard pass order variation coefficient C. Generally, the standard pass order variation coefficient C should satisfy the equation... Since the standard pass order coefficient f for thinning and drawing is simplified to an approximate fitting result, the actual standard pass order variation coefficient C is also... Substituting the approximate fitting result into the approximate formula simplifies and optimizes the calculation process, enabling it to more effectively guide and determine the processing parameters for thinning. The beneficial effects of this invention are:

[0048] The processing method of this invention achieves effective copper material thinning, enabling the effective processing and preparation of ultra-thin planar copper materials, effectively preserving the mechanical properties of copper, and the overall method is suitable for industrial processing, simple, efficient and low cost. Detailed Implementation

[0049] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0050] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0051] Unless otherwise specified, the copper materials used in the embodiments of the present invention are all industrial pure copper, and the copper materials used in the embodiments of the present invention are all high-quality copper materials purchased on May 2, 2022 from the same batch. Random sampling experiments were conducted to record the copper materials of this batch. The critical deformation amount of this batch of copper materials is 15.5-15.6%, which is highly consistent. Before each experiment, a small amount of the experimental material is sampled and re-characterized.

[0052] Example 1

[0053] A method for thinning copper materials,

[0054] The method includes:

[0055] 1) Sample and characterize the copper material to be processed, and determine its initial critical deformation amount Def. c =0.155, or 15.5%, and the critical deformation amount Def obtained when the first critical deformation processing and low-temperature annealing treatment are followed by a second critical deformation processing treatment. c The value is 0.160, or 16.0%. The thickness of the copper material to be processed is 1.000±0.020mm, the target thickness is 0.050μm, and the target thinning amount is Def. t The value is 0.95, which means a 95% reduction in thickness.

[0056] 2) Substitute into the following formula to calculate the thinning deformation Def in the nth processing. n :

[0057]

[0058] In the formula: Def n This refers to the thinning deformation amount in the nth processing step, where n is a positive integer and has no unit. c F represents the initial critical deformation, which is dimensionless. n For the processing order, F is calculated. n=n, meaning the nth processing iteration, where n is a positive integer and has no unit; Def t The target thinning deformation, dimensionless; Def c ′ represents the critical deformation amount measured when the critical deformation processing is performed again after the first critical deformation processing and low-temperature annealing treatment. It has no unit.

[0059] Based on the above calculation results, the following table of processing thinning deformation is derived:

[0060] <![CDATA[Processing step F n > Single processing thinning deformation amount <![CDATA[Processing step F n > Single processing thinning deformation amount 1 0.145 6 0.097 2 0.136 7 0.088 3 0.126 8 0.078 4 0.117 9 0.069 5 0.107

[0061] 3) Thinning processing is carried out using conventional double-rolling cold rolling process. Based on the processing thinning deformation table calculated in step 2), 9 thinning processes are performed. After each thinning process, single-sided low-temperature annealing is performed at 150℃ for 30 minutes. The heating and cooling surfaces selected for each annealing are the same. The heating surface is temperature controlled by a crawler-type ceramic heater and simultaneously transported to the next thinning process equipment. The cooling surface is continuously purged with 25℃ cold nitrogen to control the temperature of the cooling surface, so that the cooling surface is always kept ≤60℃, resulting in a semi-finished product A with a thickness of about 0.036mm. Finally, a final thinning process is performed to 0.005mm to obtain a semi-finished product B. Semi-finished product B is then subjected to final annealing, with a final annealing regime of 200℃ for 50 minutes to obtain the target product.

[0062] Characterize the target product.

[0063] The characterization results are shown in the table below.

[0064] Thickness deviation Elongation at break Flexural fatigue life Vickers hardness of heated surface Vickers hardness of cooling surface ±6％ 5.6％ <![CDATA[≥3.8×10 4 Next 140HV 175HV

[0065] Comparative Example 1

[0066] The same characterization test was conducted on some high-quality commercially available rolled copper foil with a thickness of 0.050–0.060 mm. The test results are shown in the table below.

[0067] Standard thickness Thickness deviation Elongation at break Flexural fatigue life Surface Vickers hardness Commercially available product A 0.050mm ±3％ 4.7％ <![CDATA[1.2×10 4 Next 90HV Commercially available product B 0.060mm ±5％ 3.2％ <![CDATA[3.8×10 4 Next 145HV Commercially available product C 0.060mm ±5％ 2.9％ <![CDATA[3.1×10 4 Next 110HV Commercially available product D 0.050mm ±4％ 4.3％ <![CDATA[4.0×10 4 Next 135HV Commercially available product E 0.060mm ±2％ 3.6％ <![CDATA[1.5×10 4 Next 100HV

[0068] Note: Commercially available rolled copper foil products have been tested and found to have essentially the same hardness on both sides.

[0069] By comparing the product of Example 1 with the commercially available product of Comparative Example 1, it is very clear that the present invention, by producing a copper foil with a thickness of only about half that of the commercially available product, achieves virtually no decrease in flexural fatigue life, while significantly improving surface hardness and elongation at break. This demonstrates that the rolled copper foil produced by the present invention possesses excellent mechanical properties, particularly in terms of hardness and toughness.

[0070] Example 2

[0071] Based on the process and model of Example 1, different copper materials were used to perform copper thinning processes with different target thicknesses, and corresponding parameters were substituted to determine the specific process flow, in order to verify the effectiveness of the model of the present invention. See the table below for details.

[0072] Sample number Copper material thickness to be processed Target thickness <![CDATA[Def c ]]> <![CDATA[Def c ′]]> <![CDATA[Def t ]]> FF01 0.200mm 0.010mm 0.136 0.143 0.95 FF02 0.800mm 0.200mm 0.162 0.180 0.75 FF03 1.500mm 0.015mm 0.183 0.197 0.99 FF04 1.500mm 0.030mm 0.115 0.126 0.98 FF05 0.200mm 0.005mm 0.127 0.130 0.975 FF06 0.200mm 0.170mm 0.127 0.130 0.15 FF07 0.200mm 0.100mm 0.127 0.130 0.50

[0073] The standard pull-out sequence coefficient f for FF06 is 2, which does not meet the requirement of f≥3, and Def t <0.5 is also not optimal and should be controlled. t The standard is ≥0.5, therefore the actual preparation effect is relatively limited. The above samples were characterized in the same way as in Example 1, and the characterization results are shown in the table below.

[0074]

[0075] Through the above verification and characterization, it can be seen from the FF01-FF05 experimental groups that the model of the present invention and the formula for the deformation amount in a single processing are reliable. Furthermore, the FF06-FF07 experimental groups also verified to some extent the thinning deformation amount Def in the nth processing of the present invention. n The effectiveness and applicability of the underlying Finite Element Analysis model were tested through repeated orthogonal experiments. The results showed that the present invention should at least meet the requirement of a standard pull-out sequence coefficient f ≥ 3, and preferably meet the requirement of Def. t A standard of ≥0.5 is used to achieve the best processing results.

[0076] This is because the mechanical property advantages of near-critical processing in this invention are generated through multiple accumulations, including the standard drawing sequence coefficient f and the target thinning deformation amount Def. t Too small a value will actually affect the accumulation process.

[0077] Comparative Example 2

[0078] The same characterization test was performed on some high-quality commercially available electrolytic copper foil with a thickness of 0.004 to 0.005 mm. The test results are shown in the table below.

[0079] Standard thickness Thickness deviation Elongation at break Flexural fatigue life Surface Vickers hardness Commercially available product F 0.004mm ±4％ 0.9％ <![CDATA[5.6×10 3 Next 42HV Commercially available product G 0.005mm ±2％ 1.0％ <![CDATA[3.7×10 3 Next 45HV Commercially available product H 0.005mm ±3％ 1.0％ <![CDATA[8.2×10 3 Next 38HV Commercially available product I 0.005mm ±2％ 0.8％ <![CDATA[4.2×10 3 Next 43HV Commercially available product J 0.005mm ±2％ 0.8％ <![CDATA[5.1×10 3 Next 51HV

[0080] Note: Commercially available electrolytic copper foil products have been tested and found to have essentially the same hardness on both the rough and smooth surfaces.

[0081] By comparing the FF05 sample in Example 2 with the commercially available product in Comparative Example 2, it is very clear that the copper foil prepared by the near-critical thinning rolling process of this invention exhibits extremely high mechanical properties while maintaining a thickness comparable to electrolytic copper foil. However, existing rolled copper foils cannot produce ultra-thin copper foils with a thickness of only 0.005 mm. Therefore, the copper foil of this invention achieves the preparation of ultra-thin rolled copper foil through near-critical processing, and also optimizes the mechanical properties of the rolled copper foil significantly.

[0082] Comparative Example 3

[0083] Based on the same material as in Example 1, the single-process thinning deformation amount was adjusted for different processing sequences, resulting in the following processing thinning deformation table:

[0084] Processing sequence Single processing thinning deformation amount Processing sequence Single processing thinning deformation amount 1 0.16 6 0.09 2 0.14 7 0.07 3 0.13 8 0.06 4 0.12 9 0.05 5 0.11 10 0.02

[0085] In the above processing, after the first to ninth processing steps are completed, a single-sided low-temperature annealing is performed at 150℃ for 30 minutes. The heating and cooling surfaces selected for each annealing are the same. The heating surface is controlled by a tracked ceramic heater and simultaneously conveyed to the next thinning processing equipment. The cooling surface is continuously purged with 25℃ cold nitrogen gas to control the temperature of the cooling surface, so that the cooling surface is always kept ≤60℃, resulting in a semi-finished product. After processing step 10, the semi-finished product undergoes final annealing, which is performed at 200℃ for 50 minutes to obtain the target product.

[0086] Characterize the target product.

[0087] The characterization results are shown in the table below.

[0088] Thickness deviation Elongation at break Flexural fatigue life Vickers hardness of heated surface Vickers hardness of cooling surface ±4％ 4.1％ <![CDATA[≥3.6×10 4 Next 135HV 140HV

[0089] Compared with Example 1, it can be found that the mechanical properties of the product obtained in this comparative example show a very significant decrease, especially in terms of elongation at break and surface hardness. Furthermore, the surface hardness exhibits very little difference between the two sides, indicating that it did not undergo near-critical processing. Near-critical processing would cause differences in grain size between the two sides, but this comparative example does not show this phenomenon. In addition, similar experiments were conducted, and the results show that controlling the single-process thinning deformation Def... n At that time, it can make the actual amount of operation slightly less than the calculated Def. n However, it should generally not exceed the calculated Def. n The core of this invention lies in achieving a grain size gradient difference through single-sided low-temperature annealing after the grains are controllably coarsened to near their limit, thereby producing superior mechanical properties. Furthermore, when the actual operating quantity is significantly greater than the calculated Def...n However, since it already achieves grain refinement, it cannot achieve the technical effect required by this invention. Furthermore, when the actual operating quantity is slightly less than Def... n Even at that time, it can still produce some effect.

[0090] Through testing, it was found that, in actual operation, controlling Def... n ×0.9 < Actual operating volume <Def n Within the range of ×1.02, relatively better processing and preparation effects can generally be achieved.

Claims

1. A method for thinning copper materials, characterized in that, The method includes: 1) Obtain the initial critical deformation Def of the copper material to be processed. c Data and standard track sequence variation coefficient C; 2) Based on the target thinning deformation amount Def t The standard pass sequence coefficient f for thinning and drawing is calculated using the following formula: In the formula: f is the standard sequence coefficient for thinning and drawing, satisfying f≥3, and has no unit; Def t The target thinning deformation, dimensionless; Def c , where C is the initial critical deformation, dimensionless; C is the standard track sequence variation coefficient, dimensionless. 3) Calculate the thinning deformation Def in the nth processing step. n Based on the calculation results, the single processing amount during the copper material thinning process is controlled, and the thinning deformation amount Def in the nth processing is determined. n The calculation is performed using the following formula: In the formula: Def n This refers to the thinning deformation amount in the nth processing step, where n is a positive integer and has no unit. c F represents the initial critical deformation, which is dimensionless. n The processing order is defined by n, which is a positive integer with no unit; f is the standard pass order coefficient for thinning and drawing, which satisfies f≥3 and has no unit. 4) Based on the calculation results of step 3), perform F on the copper material to be processed. n The thinning process is repeated until the target thickness is achieved. Except for the final thinning process, the deformation amount during each thinning process is controlled to conform to the deformation amount Def of the nth thinning process in step 3). n According to the calculation results, the copper material was subjected to low-temperature annealing after the first to the penultimate thinning process, and final annealing was carried out after the last thinning process to complete the copper material thinning process. Step 1) The standard track sequence variation coefficient C is calculated by the following formula: In the formula: C is the standard track sequence variation coefficient, which has no unit; Def c This is the initial critical deformation, dimensionless; Def c ′ represents the critical deformation amount measured during the second critical deformation processing after the first critical deformation processing and low-temperature annealing treatment. It has no unit.

2. The method for thinning copper material according to claim 1, characterized in that, The low-temperature annealing is performed at 120–150°C for 25–35 minutes.

3. The method for thinning copper material according to claim 1, characterized in that, Step 4) The final annealing is performed at 180-220℃ for 30-60 minutes.

4. A method for thinning copper material according to claim 1, 2, or 3, characterized in that, The method is used for processing plate-shaped, sheet-shaped, or foil-shaped copper materials.

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