Annealing method of copper strip foil

Abstract

The invention relates to the technical field of copper strip foil production, and provides a copper strip foil annealing method. Internal stress is released in advance through the first heat preservation treatment and the second heat preservation treatment, and interlayer extrusion adhesion caused by material recrystallization and severe material thermal expansion at high temperature in the third heat preservation treatment is reduced; moreover, slow cooling is carried out in a controllable cooling mode, so that new internal stress caused by rapid cooling can be prevented, the temperature difference between the interior and the exterior of the material coil is reduced, new stress of cooling inner and outer rings is eliminated, and the defect that gaps between layers of the material coil are reduced due to high-temperature atom diffusion and severe thermal deformation in the annealing process is overcome; the purpose that copper strip foil layers are not adhered after annealing is achieved. Results of the embodiment show that after the copper strip foil is annealed and softened by the method provided by the invention, the interlayer adhesion is avoided, the surface quality is excellent, the problem of interlayer adhesion after the copper strip foil whole-series products, especially the ultrathin copper strip foil is annealed, is solved, and the production efficiency can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of copper strip foil production, and in particular to an annealing method for copper strip foil. Background Art

[0002] Copper foil is a thin strip of metal material with copper as the main component. It is widely used in electronic circuits, batteries and electromagnetic shielding.

[0003] Annealing is a necessary step in the production process of copper foil. The bell-shaped annealing furnace is the most common annealing equipment in the copper foil industry. The equipment has the characteristics of small footprint, low price, strong applicability, energy saving and environmental protection. At the same time, its annealing is not limited by the material and thickness of the foil. It is an irreplaceable equipment in the preparation of soft products with a thickness of 0.006-0.05mm thin foil. Soft thin foil with a thickness of 0.05mm and below is a necessary product for the manufacture of electronic products such as copper foil tapes, soft connections, and die-cut circuits. With the widespread popularization of lightweight and miniaturized electronic equipment and the increasing pressure on cost and quality requirements of the electronics industry, the thickness of copper foil is getting thinner and thinner while meeting functionality, and the surface quality requirements are getting higher and higher. Compared with thick materials, the overall strength of thin foil is lower after annealing and softening. Slight interlayer bonding will cause subsequent adhesion deformation and folding, which seriously affects its appearance quality and use effect.

[0004] At present, in order to meet application requirements and reduce production difficulty, the industry usually uses higher purity copper or performs special anti-corrosion on the surface before annealing to reduce or eliminate the phenomenon of adhesion between thin foil layers. However, whether using purer copper or performing special anti-corrosion, the cost will be greatly increased. Summary of the invention

[0005] In view of this, the present invention provides a method for annealing a copper foil. The annealing method provided by the present invention is used to anneal the copper foil. After the copper foil is annealed and softened, the interlayers are non-adhesive and the surface quality is excellent. The method is suitable for annealing extremely thin copper foil, which can greatly improve production efficiency and has low cost.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for annealing a copper foil strip comprises the following steps: subjecting the copper foil strip to a first heat preservation treatment, a second heat preservation treatment and a third heat preservation treatment in sequence, and then subjecting the copper foil strip to controllable cooling, air cooling and water cooling in sequence;

[0008] The temperature of the first heat preservation treatment is 120-150° C., and the heat preservation time is 0.5-3 hours;

[0009] The temperature of the second heat preservation treatment is 230-250°C, and the heat preservation time is 0.5-3h;

[0010] The temperature of the third heat preservation treatment is the recrystallization temperature of the copper foil, and the heat preservation time is 3 to 6 hours;

[0011] The cooling rate of the controllable cooling is ≤40°C / h; the terminal temperature of the controllable cooling is 200-230°C.

[0012] Preferably, the pressure of the first heat preservation treatment, the second heat preservation treatment and the third heat preservation treatment is 1.1×10 6 ~1.5×10 6 Pa.

[0013] Preferably, the heating rate to the temperature of the first insulation treatment is 0.5 to 1.5°C / min; the heating rate to the temperature of the second insulation treatment is 0.5 to 1.5°C / min; the heating rate to the temperature of the third insulation treatment is 0.5 to 1.5°C / min.

[0014] Preferably, the protective atmosphere of the first insulation treatment, the second insulation treatment and the third insulation treatment is a hydrogen-nitrogen mixture; the volume fraction of hydrogen in the hydrogen-nitrogen mixture is 5-20%, and the volume fraction of nitrogen is 80-95%; the oxygen content of the hydrogen-nitrogen mixture is below 100 ppm.

[0015] Preferably, the recrystallization temperature of the copper foil is 230-350°C.

[0016] Preferably, the annealing of the copper foil is carried out in a bell-type annealing furnace; the bell-type annealing furnace is provided with an external multi-branch temperature controller; the external multi-branch temperature controller comprises a display and a plurality of independent branch probes, the display is external, and the branch probes are placed in the heating cover of the bell-type annealing furnace;

[0017] An oxygen analyzer is provided in the atmosphere proportioning station of the bell-type annealing furnace.

[0018] Preferably, the controllable temperature reduction includes: stopping heating, and controlling the temperature reduction rate in the furnace to ≤40°C / h by adjusting the height of the heating cover of the bell-shaped annealing furnace.

[0019] Preferably, the method for adjusting the height of the heating hood of the bell-type annealing furnace includes: placing a controllable adjustable cooling device at the bottom of the heating hood, and adjusting the height of the heating hood by controlling the height of the controllable adjustable cooling device; the controllable adjustable cooling device includes a support plate and a plurality of support legs arranged at the bottom of the support plate; the support plate is an annular plate; the support legs include a support frame, an adjustable hydraulic rod connected to the support frame, and a fixed base arranged at the bottom of the adjustable hydraulic rod.

[0020] Preferably, the terminal temperature of the air cooling is 100-120°C.

[0021] Preferably, the copper foil is made of pure copper, oxygen-free copper, phosphorus-deoxidized copper or silver-copper alloy.

[0022] The invention provides an annealing method for a copper foil strip, comprising the following steps: subjecting the copper foil strip to a first insulation treatment, a second insulation treatment and a third insulation treatment in sequence, and then subjecting the copper foil strip to controllable cooling, air cooling and water cooling in sequence; the temperature of the first insulation treatment is 120-150°C, and the insulation time is 0.5-3h; the temperature of the second insulation treatment is 230-250°C, and the insulation time is 0.5-3h; the temperature of the third insulation treatment is the recrystallization temperature of the copper foil strip, and the insulation time is 3-6h; the cooling rate of the controllable cooling is ≤40°C / h; and the terminal temperature of the controllable cooling is 200-230°C. The present invention releases internal stress in advance through the first and second heat preservation treatments, and reduces the interlayer extrusion and adhesion caused by material recrystallization and severe thermal expansion of materials at high temperatures during the third heat preservation treatment; and the present invention performs slow cooling in a controllable cooling manner, which can prevent new internal stresses from being generated due to rapid cooling, reduce the temperature difference between the inside and outside of the coil, eliminate the new stress of the inner and outer circles due to cooling, and compensate for the reduction in the interlayer gap of the coil caused by high-temperature atomic diffusion and severe thermal deformation inside and outside during the annealing process, so as to achieve the purpose of non-adhesion between the layers of the copper foil after annealing. The results of the embodiment show that the copper foil provided by the method of the present invention does not adhere to the layers after annealing and softening, and has excellent surface quality, which solves the problem of interlayer adhesion of the entire series of copper foil products, especially ultra-thin copper foil, after annealing, and can greatly improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of a bell-type annealing furnace; 1 is a heating cover and a heat preservation layer, 2 is a heat preservation cover, 3 is a convection fan, 4 is a temperature controller provided by the equipment, 5 is an external multi-point temperature controller, 6 is a cooling cover (with a built-in air-cooling and water-cooling system), 7 is an atmosphere proportioning station, 8 is a hydrogen proportioning station, and 9 is an oxygen analyzer;

[0024] Figure 2 Schematic diagram of the structure of the controllable cooling device; 10 is a support plate, 11 is a support frame, 12 is a fixed base, and 13 is an adjustable hydraulic rod (with scale);

[0025] Figure 3 This is a graph showing the relationship between the height of the controllable cooling device and the cooling rate. DETAILED DESCRIPTION

[0026] The invention provides a method for annealing a copper foil, comprising the following steps: subjecting the copper foil to a first heat preservation treatment, a second heat preservation treatment and a third heat preservation treatment in sequence, and then subjecting the copper foil to controllable cooling, air cooling and water cooling in sequence.

[0027] In the present invention, the annealing of the copper foil is specifically carried out in a bell-type annealing furnace, and the bell-type annealing furnace is provided with an external multi-branch temperature controller; the external multi-branch temperature controller includes a display and a plurality of independent branch probes, the display is external, and the branch probes are placed in the heating cover of the bell-type annealing furnace; in the present invention, the number of branch probes of the external multi-branch temperature controller is preferably 3 to 4, and each branch probe can independently measure the temperature; in a specific embodiment of the present invention, it is preferred to place a branch probe next to each layer of copper foil coil, Or the temperature of the bottom layer of coils is measured by the temperature controller of the bell-shaped annealing furnace, and a branch probe is placed in each layer starting from the second layer of coils; in the present invention, the temperature of the branch probe that reaches the target temperature first is used as the standard during the heating stage (such as heating for the first insulation treatment, heating for the second insulation treatment, and heating for the third insulation treatment). In a specific embodiment of the present invention, the temperature of the bottom layer branch probe or the temperature controller of the bell-shaped annealing furnace can be used directly as the standard; during the cooling stage (controllable cooling, air cooling, and water cooling), the temperature of the branch probe with the lowest temperature is used as the standard. The temperature controller of the bell-shaped annealing furnace is at the bottom of the furnace body. There is a temperature difference between the upper and lower parts of the furnace body. The temperature measurement using the built-in temperature controller cannot accurately and effectively measure the real-time temperature of the upper and lower parts of the entire furnace body. In order to better study and control process parameters, the present invention adds an external multi-point temperature controller on the basis of the function of the bell-shaped annealing furnace equipment itself, which can better monitor the actual temperature of the material at each position in real time.

[0028] In the present invention, an oxygen analyzer is provided in the atmosphere proportioning station of the bell-shaped annealing furnace; the present invention has no special requirements for other structures of the bell-shaped annealing furnace, and those familiar to those skilled in the art can be adopted. In the present invention, the structural schematic diagram of the bell-shaped annealing furnace is as follows Figure 1 In a specific embodiment of the present invention, the copper foil coil is preferably placed in a bell-shaped annealing furnace, and the copper foil coil is preferably placed in a hanging or lying manner and cannot be piled up on each other.

[0029] In the present invention, the annealing of the copper foil is specifically soft annealing.

[0030] In the present invention, the temperature of the first insulation treatment is 120-150°C, specifically 120°C, 130°C, 140°C or 150°C; the insulation time of the first insulation treatment is preferably 0.5-3h, specifically 0.5h, 1h, 2h or 3h; the heating rate to the temperature of the first insulation treatment is preferably 0.5-1.5°C / min, specifically 1°C / min.

[0031] In the present invention, the temperature of the second heat preservation treatment is 230-250°C, specifically 230°C, 240°C or 250°C, and the heat preservation time of the second heat preservation treatment is 0.5-3h, specifically 0.5h, 1h, 2h or 3h; the heating rate to the temperature of the second heat preservation treatment is preferably 0.5-1.5°C / min, specifically 1°C / min. In the present invention, the first heat preservation treatment and the second heat preservation treatment are used to release the internal stress of the copper foil in advance.

[0032] In the present invention, the temperature of the third heat preservation treatment is the recrystallization temperature of the copper foil, and the heat preservation time is preferably 3 to 6 hours, specifically 3 hours, 4 hours, 5 hours or 6 hours; the recrystallization temperature of the copper foil is preferably 230 to 350°C; the material of the copper foil is preferably pure copper, oxygen-free copper, phosphorus deoxidized copper or silver-copper alloy. The present invention is suitable for annealing copper foil products of various widths and thicknesses, and is particularly effective for thin copper foils with a thickness of 0.006 to 0.1 mm that are difficult to produce in the industry.

[0033] In the present invention, the pressure of the first heat preservation treatment, the second heat preservation treatment and the third heat preservation treatment is preferably 1.1×10 6 ~1.5×10 6 Pa. The protective atmosphere of the first insulation treatment, the second insulation treatment and the third insulation treatment is preferably a hydrogen-nitrogen mixture; the volume fraction of hydrogen in the hydrogen-nitrogen mixture is 5-20%, specifically 5%, 10%, 15% or 20%, and the volume fraction of nitrogen is preferably 80-95%, specifically 80%, 85%, 90% or 95%; the oxygen content of the hydrogen-nitrogen mixture is preferably less than 100ppm. In the present invention, for the stability and safety of the oxygen content, the present invention installs an oxygen content analyzer in the atmosphere proportioning station of the bell-type annealing furnace to control the oxygen content. The main component of the protective atmosphere used in the annealing of the present invention is nitrogen, because oxygen reacts with copper at high temperature to cause severe oxidation of the copper foil, while nitrogen does not react with copper and can achieve bright annealing. In addition, in order to improve the thermal conductivity of the atmosphere and prevent the nitrogen purity from being insufficient (containing a small amount of oxygen), the present invention adds a small amount of hydrogen. On the one hand, hydrogen can reduce oxidized copper at high temperature, and on the other hand, hydrogen has good thermal conductivity. Adding hydrogen can increase the thermal conductivity of the atmosphere and improve the thermal conduction efficiency. In addition, the present invention controls the oxygen content in the protective atmosphere and can also prevent the copper foil from being oxidized by oxygen.

[0034] In a specific embodiment of the present invention, after the copper foil is placed in a bell-type annealing furnace, it is preferred to first evacuate the copper foil to a temperature of 1.0×10 -3 pa, then fill with inert gas, and then fill with hydrogen-nitrogen mixed gas to make the pressure in the furnace reach 1.1×10 6 ~1.5×106 Pa, and then start heating to carry out the first heat preservation treatment.

[0035] In the present invention, the cooling rate of the controllable cooling is preferably ≤40°C / h, more preferably 20-35°C / h, specifically 28°C / h, 29°C / h, 31°C / h or 35°C / h; the terminal temperature of the controllable cooling is preferably 200-230°C, specifically 200°C, 210°C, 220°C or 230°C; the controllable cooling preferably includes: stopping heating, and controlling the cooling rate to ≤40°C / h by adjusting the height of the heating cover of the bell-type annealing furnace; no heating is required during the controllable cooling process, and only the protective atmosphere and the convection fan at the bottom of the furnace need to be kept running.

[0036] In the present invention, the method of adjusting the height of the heating hood of the bell-type annealing furnace preferably includes: placing a controllable and adjustable cooling device at the bottom of the heating hood, and adjusting the height of the heating hood by controlling the height of the controllable and adjustable cooling device; the controllable and adjustable cooling device preferably includes a support plate and a plurality of support legs arranged at the bottom of the support plate; the support legs include a support frame, an adjustable hydraulic rod connected to the support frame, and a fixed base arranged at the bottom of the adjustable hydraulic rod; the support plate is an annular plate; the adjustable hydraulic rod has a scale for controlling the height of the controllable and adjustable cooling device; the number of the support legs is preferably 3, which are evenly distributed on the circumference of the support plate. During the controllable cooling period, the temperature changes in the furnace are monitored in real time by an external multi-point temperature controller. In the present invention, the structural schematic diagram of the controllable and adjustable cooling device is as shown in the figure Figure 2 shown.

[0037] The amount of furnace loading and the outside temperature will affect the cooling rate in the furnace. In view of the problem that the cooling rate is seriously affected by the different amounts of furnace loading and the temperature changes in the four seasons, the present invention has produced a controllable cooling device, which can adjust the height of the heating cover by the height of the controllable cooling device, thereby controlling the cooling rate in the furnace. In a specific embodiment of the present invention, the relationship between the cooling rate and the height of the controllable cooling device under different amounts of furnace loading and ambient temperatures can be formulated through preliminary experiments and statistical analysis, thereby realizing the control of the cooling rate in the controllable cooling stage. In a specific embodiment of the present invention, the higher the height of the controllable cooling device, the greater the cooling rate in the furnace. When the outside temperature is 15°C and the amount of furnace loading is 7.5 tons, the height of the controllable cooling device is within the range of 50 to 110 cm, and the cooling rate of the controllable cooling device can be controlled to be below 40°C / h; the height of the controllable cooling device (i.e., the lifting height of the heating cover) is the distance from the surface of the support plate to the bottom of the fixed base. The present invention controls the cooling rate in the furnace by controlling the height of the controllable cooling device, and combines the built-in temperature controller of the equipment and the external multi-point temperature controller to monitor the temperature in the furnace in real time, thereby realizing autonomous control of the cooling rate, so that the cooling rate of the controllable cooling process is not limited by the external environment and the furnace loading, thereby ensuring the success rate and achieving the non-stick annealing effect of the copper foil.

[0038] After the temperature is controllably lowered to 200-230° C., the present invention starts air cooling, and the terminal temperature of the air cooling is preferably 100-120° C., specifically 100° C., 110° C. or 120° C. The present invention has no special requirements for the cooling rate of the air cooling, and a temperature well known to those skilled in the art can be used.

[0039] After the temperature is cooled to 100-120° C. by air cooling, the present invention starts water cooling; the end point of the water cooling is room temperature; the present invention has no special requirements on the cooling rate of the water cooling, and a rate familiar to those skilled in the art can be adopted.

[0040] In a specific embodiment of the present invention, after the controllable cooling is completed, the heating cover of the bell-type annealing furnace is switched to a cooling cover, and the cooling cover has its own air cooling and water cooling system for air cooling and water cooling.

[0041] In the present invention, after being cooled to room temperature by water cooling, the copper foil which has been cooled to room temperature is preferably stabilized for 1 to 4 hours before being taken out of the furnace, thereby preventing the copper foil from being oxidized due to the reverse temperature of the furnace body.

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] Taking T2 pure copper with a recrystallization temperature of 340°C as an example, the annealing process is verified and implemented. The device used is a bell-type annealing furnace, which is provided with an external multi-point temperature controller. The display of the multi-point temperature controller is external, and the branch probe is placed in the heating cover of the bell-type annealing furnace. There are 4 branch probes in total, one is placed next to each layer of copper strip foil coil; the atmosphere proportioning station of the bell-type annealing furnace is provided with an oxygen analyzer, and the structural schematic diagram is shown in FIG. Figure 1 shown.

[0045] Copper foil coils with a thickness of 0.01 mm and a roll weight of 150 kg per roll, a quantity of 50 rolls (total weight of 7500 kg) were placed (the material placement method was hanging type, with a total of 4 layers) in a bell-type annealing furnace, and the equipment was evacuated to 1.0×10 - 3 Pa, then fill with inert gas, and then fill with a protective atmosphere with a hydrogen content of 5vol%, a nitrogen content of 95vol%, and an oxygen content controlled below 100ppm. Ensure that the pressure in the furnace is 1.2×10 6 Pa, then heated to 150℃ at a heating rate of 1.0℃ / min and kept warm for 1 hour for the first insulation treatment. After the first insulation treatment, continue to heat to 250℃ at a heating rate of 1.0℃ / min and keep warm for 1 hour for the second insulation treatment. After the second insulation treatment, heat to 340℃ at a heating rate of 1.0℃ / min and keep warm for 3 hours. Then stop heating, and only need to pass the protective atmosphere and keep the convection fan at the bottom of the furnace running, and then use the crane to lift the heating cover and add the controllable cooling device and adjust the specified height (specific height and cooling rate see Table 1) for cooling. During this period, the temperature change in the furnace is monitored by the external multi-point temperature controller. After cooling to 200℃, it is cooled to 120℃ by air cooling, and then cooled to room temperature by water cooling. It is stabilized for 2 hours to prevent overheating, and then it is packaged out of the furnace.

[0046] In a workshop temperature of 15°C, the copper material with a recrystallization temperature of 340°C was annealed according to the above conditions. The time taken to reduce the temperature from 340°C to 200°C and the adhesion situation were statistically analyzed. The results are shown in Table 1.

[0047] Comparative Example 1

[0048] The other conditions are the same as those in Example 1, except that the height of the controllable cooling device is changed. The specific height is shown in Table 1. The time taken to cool from 340°C to 200°C and the adhesion condition are statistically analyzed, and the results are shown in Table 1.

[0049] Reference example

[0050] The other conditions were the same as those in Example 1, except that the temperature was raised to 200°C after the first heat preservation treatment, and then directly kept at 200°C for 3 hours, followed by air cooling and water cooling. The softening and sticking of the copper foil were observed, and the results are shown in Table 1.

[0051] Figure 3 This is a graph showing the relationship between the height of the controllable cooling device and the cooling rate.

[0052] Table 1 Experimental results of embodiments, comparative examples and reference examples

[0053]

[0054] It can be seen from the above embodiments that, when the external environment is 15°C and the furnace load is 7.5 tons, when annealing the copper series materials with a high recrystallization temperature, while ensuring that the stress relief (first insulation treatment and second insulation treatment) state in the heating stage is intact, the cooling rate in the controllable cooling stage is controlled to be lower than 40°C / h, which can effectively eliminate the stress caused by atomic migration in the third insulation treatment process, and avoid the cooling stress caused by rapid cooling, so as to achieve the effect of no sticking. According to the above comparative examples, it can be seen that when the cooling rate in the controllable cooling process is too fast, exceeding 40°C / h, sticking will occur, and as the cooling rate increases, the sticking will become more serious.

[0055] In addition, it can be seen from the reference example that the material does not soften at 200°C, and no obvious atomic migration occurs between the foil layers. Under the condition that the stress relief is in place during the heating stage (the first insulation treatment and the second insulation treatment), the internal stress generated by rapid cooling below 200°C is not enough to cause tape sticking, indicating that the internal stress generated by the water cooling and air cooling of the equipment at this temperature has almost no effect on the tape sticking. Therefore, the present invention can directly perform air cooling and water cooling after the temperature is controllably lowered to 200°C.

[0056] The above results show that the present invention can adjust the position of the controllable cooling device according to different external ambient temperatures and different furnace loadings, and combine the equipment's own temperature controller and an external multi-point temperature controller to monitor the furnace temperature in real time, so as to achieve controllable cooling rate and finally achieve the effect of non-stick annealing of copper foil.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for annealing a copper foil, characterized in that: The following steps are involved: The copper foil is sequentially subjected to a first heat preservation treatment, a second heat preservation treatment and a third heat preservation treatment, and then sequentially subjected to controllable cooling, air cooling and water cooling; The temperature of the first heat preservation treatment is 120-150° C., and the heat preservation time is 0.5-3 hours; The temperature of the second heat preservation treatment is 230-250°C, and the heat preservation time is 0.5-3h; The temperature of the third heat preservation treatment is the recrystallization temperature of the copper foil, and the heat preservation time is 3 to 6 hours; The cooling rate of the controllable cooling is ≤40°C / h; the terminal temperature of the controllable cooling is 200-230°C.

2. The annealing method according to claim 1, characterized in that: The pressure of the first heat preservation treatment, the second heat preservation treatment and the third heat preservation treatment is 1.1×10 6 ~1.5×10 6 Pa.

3. The annealing method according to claim 1, characterized in that: The heating rate to the temperature of the first insulation treatment is 0.5 to 1.5°C / min; the heating rate to the temperature of the second insulation treatment is 0.5 to 1.5°C / min; the heating rate to the temperature of the third insulation treatment is 0.5 to 1.5°C / min.

4. The annealing method according to claim 1, characterized in that: The protective atmosphere of the first insulation treatment, the second insulation treatment and the third insulation treatment is a hydrogen-nitrogen mixture; the volume fraction of hydrogen in the hydrogen-nitrogen mixture is 5-20%, and the volume fraction of nitrogen is 80-95%; the oxygen content of the hydrogen-nitrogen mixture is below 100ppm.

5. The annealing method according to claim 1, characterized in that: The recrystallization temperature of the copper foil is 230-350°C.

6. The annealing method according to claim 1, characterized in that: The annealing of the copper foil is carried out in a bell-type annealing furnace; the bell-type annealing furnace is provided with an external multi-point temperature controller; the external multi-point temperature controller includes a display and a plurality of independent branch probes, the display is external, and the branch probes are placed in the heating cover of the bell-type annealing furnace; An oxygen analyzer is provided in the atmosphere proportioning station of the bell-type annealing furnace.

7. The annealing method according to claim 6, characterized in that: The controllable temperature reduction includes: stopping heating, and controlling the temperature reduction rate in the furnace to be ≤40°C / h by adjusting the height of the heating cover of the bell-shaped annealing furnace.

8. The annealing method according to claim 7, characterized in that: The method for adjusting the height of the heating hood of the bell-type annealing furnace includes: placing a controllable and adjustable cooling device at the bottom of the heating hood, and adjusting the height of the heating hood by controlling the height of the controllable and adjustable cooling device; the controllable and adjustable cooling device includes a support plate and a plurality of support legs arranged at the bottom of the support plate; the support plate is an annular plate; the support legs include a support frame, an adjustable hydraulic rod connected to the support frame, and a fixed base arranged at the bottom of the adjustable hydraulic rod.

9. The annealing method according to claim 1, characterized in that: The terminal temperature of the air cooling is 100-120°C.

10. The annealing method according to claim 1, characterized in that: The copper foil is made of pure copper, oxygen-free copper, phosphorus-deoxidized copper or silver-copper alloy.

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