Pulsed magnetic field treatment method for eliminating residual stress of copper alloy thin strip

Abstract

The invention discloses a pulsed magnetic field treatment method for eliminating residual stress of a copper alloy thin strip, and belongs to the technical field of performance improvement of alloy plates and strips. In order to solve the problems that the residual stress of a copper alloy plate strip cannot be effectively reduced and the etching performance of the copper alloy plate strip cannot be effectively improved while the strength-conductivity of the copper alloy plate strip is weighed at present, the method comprises the following steps: introducing a pulsed magnetic field in alloy casting, hot rolling, cold rolling and annealing processes for multiple composite treatments; according to the method, the residual stress in the alloy can be obviously reduced and even eliminated, the strength and the conductivity of the alloy strip are improved to a certain extent, and the method is suitable for the final etching process of the alloy strip so as to meet the performance requirement of the copper alloy strip for the lead frame.

Description

Technical Field

[0001] The invention belongs to the technical field of improving the performance of alloy plates and strips, and specifically relates to a pulsed magnetic field treatment method for eliminating residual stress in a copper alloy thin strip. Background Art

[0002] The integrated circuit industry is the focus of current and future global technological competition. At present, copper alloy lead frames are the chip carriers of integrated circuits, the channels for chip information to contact the outside world, and are also very important basic materials in the semiconductor industry. The copper alloy strips used for lead frames are mainly produced by chemical etching. Although etching, as a stress-free processing method, can achieve the production of high-density, multi-pin lead frames, this method will bring more stringent requirements on the internal stress, warping, surface quality, etching performance, etc. of the copper alloy strips. Rolled copper alloy strips will warp due to uneven stress release during etching, which seriously affects the subsequent use of the product. Therefore, with the continuous improvement of product performance requirements, how to effectively reduce the residual stress and improve the etching performance of copper alloy strips while balancing the strength-conductivity of copper alloy strips has become an important topic of current research.

[0003] As we all know, the plasticity of almost all metal materials in a magnetic field will change to a certain extent, thereby improving their performance such as wear resistance, fatigue life and resistivity. Pulsed magnetic field can effectively reduce the residual stress of materials and improve the performance of materials by affecting dislocation movement, magnetostriction effect, selective grain deformation, dislocation proliferation and stress relaxation, and homogenization of residual stress. Compared with the commonly used heat treatment methods, magnetization treatment has the characteristics of simple operation, low investment, quick effect and no pollution. Studies have shown that magnetic annealing has a significant effect on the texture and microstructure evolution of non-ferrous metal alloys. The influence and regulation of magnetic field annealing on the microstructure and texture of metal materials is still a hot topic of concern to many scholars. The effect of magnetic field annealing on texture, microstructure and magnetism is still an important research direction for scientists, and the exploration of its internal mechanism is still a long way to go. Summary of the invention

[0004] In view of the current problem that it is impossible to balance the strength and conductivity of copper alloy strips while effectively reducing their residual stress and improving their etching performance, the present invention provides a pulsed magnetic field treatment method for eliminating residual stress of copper alloy strips. By optimizing the process of adding magnetic field treatment to some processes in the entire industrial chain of copper alloy strips, copper alloy strips with excellent performance are prepared, which provides a reference for breakthroughs in the manufacturing technology of copper alloy strips for high-precision etching lead frames required for integrated circuits and the development of the industry, and continuously improves the precision forming quality of copper alloy strips.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A pulse magnetic field treatment method for eliminating residual stress in a copper alloy thin strip comprises the following steps:

[0007] Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1000°C to 1300°C to form an alloy melt, which is then injected into a mold for cooling and casting to obtain an ingot; the entire melting and casting process is carried out in a magnetic field, and the pulsed magnetic field treatment of the molten alloy promotes the uniform distribution of the solute and the temperature field, making the solidified structure more uniform and the grains finer, thereby improving the hardness and strength of the ingot to a certain extent;

[0008] Step 2, solution treatment: under the action of pulsed magnetic field, heat and keep the ingot warm at 800℃~1350℃ for 0.5h~24h, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; pulsed magnetic field treatment is also performed to dissolve the second phase in the alloy completely or maximally into the solid solution matrix. At the same time, the stress caused by cold and hot processing can be eliminated, the alloy can be recrystallized, and the performance of the material can be significantly improved.

[0009] Step 3, hot rolling: hot rolling the solution treated ingot under the action of a pulsed magnetic field, and finally obtaining a copper alloy slab with a thickness of 10 mm to 20 mm; and introducing a magnetic field during the hot rolling process to improve the alloy properties;

[0010] Step 4, cold rolling: under the action of a pulsed magnetic field, the copper alloy slab is cold rolled N times, where N is any positive integer, until the thickness requirement is met to obtain a copper alloy thin strip; a pulsed magnetic field is introduced during the cold rolling process to improve the alloy properties.

[0011] Step 5, tension annealing: under the action of a pulsed magnetic field, the copper alloy strip is heated and annealed at a temperature of 100°C to 400°C and a holding time of 30s to 12h; a copper alloy strip sample with residual stress eliminated is obtained by combined heat treatment and magnetic field treatment.

[0012] Furthermore, the pulse magnetic field current is 20A to 100000A, the frequency is 20Hz to 100Hz, the duty cycle is 20% to 100%, and the magnetic induction intensity is 0 to M, where the M value is implemented according to the specific process, and M is less than the limit met by the instrument.

[0013] Furthermore, during the solution treatment in step S2, an inert gas is continuously introduced to prevent oxidation of the copper alloy ingot.

[0014] Furthermore, the holding time in step S2 needs to be adjusted according to the specific size of the ingot so that the ingot is heated evenly and the structure is homogenized.

[0015] Furthermore, the time interval for hot rolling the solution treated ingot is no more than 30 seconds.

[0016] Furthermore, the pulsed magnetic field device in steps S1, S2, and S3 should be reasonably installed according to a specific process flow so that the magnetic field is evenly distributed during the alloy preparation process.

[0017] Furthermore, the plate should be pickled before and after step S3 and step S4 to remove oxide scale and impurities to ensure the surface quality of the product.

[0018] Furthermore, in step 4, the number of cold rolling passes is 10 to 30.

[0019] Furthermore, in step S4, intermediate annealing is performed in the cold rolling gap of N cold rollings to reduce the hardness of the alloy and facilitate further cold rolling of the copper alloy slab. The intermediate annealing temperature is 100-800°C, and the insulation time is 10min-12h. The specific insulation time should be adjusted according to the size of the plate, so the insulation time is not limited thereto.

[0020] Furthermore, in step S4, a pulsed magnetic field is introduced into the copper alloy strip that has been cold rolled for multiple times. The number of times and procedures for implementing the pulsed magnetic field should be determined according to the actual production process, that is, the magnetic field treatment process can be appropriately increased as needed after the actual cold rolling production process is carried out.

[0021] Furthermore, the annealing process in step 5 adopts a tension annealing process, and a pulsed magnetic field treatment is added. The pulsed magnetic field and heating annealing are carried out simultaneously or before and after the pulsed magnetic field treatment. The residual stress inside the alloy is reduced and the alloy properties are improved through the combined effects of the magnetic field, thermal field and force.

[0022] Furthermore, the direction of the magnetic field should be controlled during the pulse magnetic field treatment process, and is not limited to the relative relationship that the magnetic field direction is perpendicular to the rolling direction.

[0023] Furthermore, the copper alloy material for the lead frame should include, in addition to the commonly used Cu-Fe series, Cu-Cr series, Cu-Ni series and other copper alloys for etching type lead frames.

[0024] Furthermore, the application of pulsed magnetic fields is not limited to copper alloys for lead frames, but may also be applicable to other processes that require reducing residual stress and improving product performance.

[0025] Furthermore, a pulse magnetic field device is added to the existing production equipment to save costs and improve production efficiency.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention introduces a pulsed magnetic field into the production process of the entire copper alloy industry chain for the first time. Through the coupling of magnetic force, mechanical force and thermal field, it reduces the residual stress inside the alloy while improving the strength, conductivity and other properties of the alloy, which is beneficial to the final etching process of lead frame forming to meet the performance requirements of copper alloy strips for lead frames.

[0028] The pulsed magnetic field technology introduced in the production process of the copper alloy industry chain has simple equipment, easy operation, economical and efficient, green and environmentally friendly, and strong applicability. It is not only suitable for performance improvement as a single process, but can also be combined with the thermal field to further reduce residual stress without affecting the performance of the original product. It does not make special requirements on alloy workpieces during the processing process, is suitable for rapid processing of alloy workpieces of various sizes and complex structures, greatly reduces production costs, and is expected to be applied to the processing of various alloy components of other categories. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Process flow chart of the treatment method of the present invention;

[0031] Figure 2 Schematic diagram of nanoindentation loading curve of the treatment method of the present invention;

[0032] Figure 3 Microstructure of the alloy (a) rolled sample (b) simultaneously subjected to magnetic field and annealing treatment. DETAILED DESCRIPTION

[0033] In order to gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description of the present invention. However, the present invention has multiple implementations and is not limited to the specific examples listed herein. The presentation of these examples is intended to deepen the comprehensive understanding of the disclosure of the present invention.

[0034] The copper alloy ingots in the following embodiments are made of copper alloy for lead frames, and Cu-0.23Fe-0.06P alloy is selected. In order to illustrate the magnetic field and the coupling effect of the magnetic field and the thermal field, the sample process flow used is as follows: Figure 1 shown.

[0035] The pulse magnetic field control conditions of this embodiment include voltage, current, frequency and duty cycle, and the direction of the magnetic field should be controlled during the pulse magnetic field processing (unless otherwise specified, the rolling direction is parallel to the magnetic field direction).

[0036] Example 1

[0037] The pulse magnetic field conditions of this embodiment are voltage 100V, peak current 100A, frequency 20Hz, and duty cycle 20%.

[0038] A pulse magnetic field treatment method for eliminating residual stress in copper alloy thin strips, such as Figure 1 As shown, the following steps are included:

[0039] Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1200°C and deoxidized to form an alloy melt, which is then poured into a casting mold for cooling and casting to obtain an ingot;

[0040] Step 2, solution treatment: under the action of a pulsed magnetic field, the ingot is heated and kept warm at a temperature of 1000°C for 12 hours, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; nitrogen is continuously introduced into the heating furnace during the solution treatment;

[0041] Step 3, hot rolling: pickling is performed before the alloy is treated, and the solution treated ingot is hot rolled under the action of a pulsed magnetic field, with a time interval of 20 seconds, and the thickness of the copper alloy slab is finally obtained to be 16.5 mm;

[0042] Step 4, cold rolling: pickling is performed before the alloy is processed, and the copper alloy slab is cold rolled for 10 times under the action of a pulsed magnetic field, and intermediate annealing is performed in the cold rolling interval at a temperature of 500° C. for a holding time of 2 h until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip;

[0043] Step 5, tension annealing: pickling is performed before the alloy is treated, and the copper alloy strip is heated and annealed while a pulsed magnetic field is passed. The annealing temperature is 200°C and the holding time is 3 minutes. Through heat treatment and magnetic field treatment and water cooling, the residual stress value is measured to be 9.8MPa, which has been transformed from the initial compressive stress to a tensile stress state. The residual stress of the copper alloy strip sample has decreased by 100%.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that:

[0046] Step 4, cold rolling: pickling is performed before the alloy is processed, and the copper alloy slab is cold rolled for 30 times under the action of a pulsed magnetic field, and intermediate annealing is performed in the cold rolling interval at a temperature of 100° C. for a holding time of 12 h until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip;

[0047] Step 5, tension annealing: pickling is performed before the alloy is treated, and the copper alloy strip is heated and annealed while a pulsed magnetic field is passed. The annealing temperature is 100°C and the holding time is 12 hours. Through heat treatment and magnetic field treatment, water cooling, the residual stress value is measured to be -50MPa, and the residual stress of the copper alloy strip sample is reduced by 65%.

[0048] Example 3

[0049] The difference between this embodiment and embodiment 1 is that:

[0050] The pulse magnetic field conditions of this embodiment are peak current 100000A, frequency 100 Hz, and duty cycle 100%.

[0051] Step 4, cold rolling: pickling is performed before the alloy is processed, and the copper alloy slab is cold rolled for 30 times under the action of a pulsed magnetic field, and intermediate annealing is performed in the cold rolling interval at a temperature of 800° C. for a holding time of 10 min until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip;

[0052] Step 5, tension annealing: pickling is performed before the alloy is treated, and the copper alloy strip is heated and annealed under the action of a pulsed magnetic field. The annealing temperature is 400°C and the holding time is 30s. Through heat treatment and magnetic field treatment and water cooling, the residual stress measurement value is 10MPa, and the residual stress of the copper alloy strip sample is reduced by 100%.

[0053] Example 4

[0054] The pulse magnetic field conditions of this embodiment are peak current 100A, frequency 20 Hz, and duty cycle 20%.

[0055] A pulse magnetic field treatment method for eliminating residual stress in a copper alloy thin strip comprises the following steps:

[0056] Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1300°C and deoxidized to form an alloy melt, which is then poured into a casting mold for cooling and casting to obtain an ingot;

[0057] Step 2, solution treatment: under the action of a pulsed magnetic field, the ingot is heated and kept warm at a temperature of 1350°C for 0.5 h, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; nitrogen is continuously introduced into the heating furnace during the solution treatment;

[0058] Step 3, hot rolling: pickling is performed before the alloy is treated, and the solution treated ingot is hot rolled under the action of a pulsed magnetic field, with a time interval of no more than 30 seconds, and the thickness of the copper alloy slab is finally obtained to be 16.5 mm;

[0059] Step 4, cold rolling: pickling is performed before the alloy is treated, and the copper alloy slab is cold rolled for 15 times (N is any positive integer) under the action of a pulsed magnetic field, and intermediate annealing is performed in the cold rolling interval at a temperature of 400° C. for a holding time of 3 h until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip;

[0060] Step 5, magnetic field treatment: pickling is performed before the alloy is treated, and the copper alloy strip is treated only under the action of a pulsed magnetic field and water-cooled. The residual stress measurement value is -122 MPa, and the residual stress of the copper alloy strip sample decreases by 15.8%.

[0061] Example 5

[0062] The difference from Example 4 is that the following steps are also included:

[0063] Step 6, tension annealing: pickling is performed before the alloy is treated, and the copper alloy strip after magnetic field treatment is heated and annealed at 400°C for 30s. The residual stress measurement value is -86.5MPa, and the residual stress of the copper alloy strip sample is reduced by 40%.

[0064] Example 6

[0065] The difference from Example 4 is that:

[0066] Step 5, tension annealing: pickling is performed before the alloy is processed, and the copper alloy strip is heated and annealed at a temperature of 400°C for 10 minutes. The residual stress measurement value is -23.1 MPa, and the residual stress of the copper alloy strip sample is reduced by 84%.

[0067] Example 7

[0068] The difference from Example 4 is that:

[0069] Step 5, tension annealing: pickling is performed before the alloy is treated, and the copper alloy thin strip is heated and annealed at an annealing temperature of 400° C. for a holding time of 10 min;

[0070] Step 6, magnetic field treatment: pickling is performed before the alloy is treated, and the tension annealed copper alloy strip is subjected to magnetic field treatment again, and the residual stress measurement value thereof is -20 MPa, and the residual stress of the copper alloy strip sample is reduced by 86.2%.

[0071] Example 8

[0072] The difference from Example 4 is that:

[0073] Step 5, magnetic field treatment: pickling is performed before the alloy is treated, and the copper alloy strip is treated only under the action of a pulsed magnetic field and water-cooled. The residual stress measurement value is -134 MPa, and the residual stress of the copper alloy strip sample decreases by 7.5%.

[0074] Example 9

[0075] The difference from Example 1 is that:

[0076] The material selected is Cu-0.45Cr-0.1Zr alloy.

[0077] The pulse magnetic field conditions of this embodiment are voltage 100V, peak current 100A, frequency 20Hz, and duty cycle 20%.

[0078] A pulse magnetic field treatment method for eliminating residual stress in copper alloy thin strips, such as Figure 1 As shown, the following steps are included:

[0079] Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1200°C and deoxidized to form an alloy melt, which is then poured into a casting mold for cooling and casting to obtain an ingot;

[0080] Step 2, solution treatment: under the action of a pulsed magnetic field, the ingot is heated and kept warm at a temperature of 1000°C for 12 hours, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; nitrogen is continuously introduced into the heating furnace during the solution treatment;

[0081] Step 3, hot rolling: pickling is performed before the alloy is treated, and the solution treated ingot is hot rolled under the action of a pulsed magnetic field, with a time interval of 20 seconds, and the thickness of the copper alloy slab is finally obtained to be 16.5 mm;

[0082] Step 4, cold rolling: pickling is performed before the alloy is processed, and the copper alloy slab is cold rolled for 10 times under the action of a pulsed magnetic field, and intermediate annealing is performed in the cold rolling interval at a temperature of 500° C. for a holding time of 2 h until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip;

[0083] Step 5, tension annealing: pickling is performed before the alloy is treated, and the copper alloy strip is heated and annealed while a pulsed magnetic field is passed. The annealing temperature is 200°C and the holding time is 3 minutes. Through heat treatment and magnetic field treatment and water cooling, the residual stress value is measured to be 2.3MPa, which has been transformed from the initial compressive stress to a tensile stress state. The residual stress of the copper alloy strip sample has decreased by 100%.

[0084] Comparative Example 1

[0085] The pulse magnetic field conditions of this embodiment are peak current 100A, frequency 20 Hz, and duty cycle 20%.

[0086] A pulse magnetic field treatment method for eliminating residual stress in a copper alloy thin strip comprises the following steps:

[0087] Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1200°C and deoxidized to form an alloy melt, which is then poured into a casting mold for cooling and casting to obtain an ingot;

[0088] Step 2, solution treatment: under the action of a pulsed magnetic field, the ingot is heated and kept warm at a temperature of 1000°C for 12 hours, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; inert gas is continuously introduced into the heating furnace during the solution treatment process;

[0089] Step 3, hot rolling: hot rolling the solution treated ingot under the action of a pulsed magnetic field, with a time interval of no more than 30 seconds, and finally obtaining a copper alloy slab with a thickness of 16.5 mm;

[0090] Step 4, cold rolling: under the action of a pulsed magnetic field, the copper alloy slab is cold rolled 10 times, and intermediate annealing is performed in the cold rolling interval at a temperature of 400°C for 10 minutes until the thickness is rolled to 0.203 mm to obtain a copper alloy thin strip; and the residual stress thereof is tested to be -144.9 MPa.

[0091] By comparing Comparative Example 1 and Example 6, it can be seen that the residual stress value of the copper alloy strip after annealing is reduced.

[0092] By comparing Comparative Example 1 with Example 1, it can be seen that the residual stress of the copper alloy strip treated with the magnetic field and annealing is reduced by 100%, and the effect is significant.

[0093] At the same time, we have also conducted systematic tests on Cu-Cr copper alloys and Cu-Ni copper alloys, and the test results can achieve the above-mentioned technical effects.

[0094] In summary, heat treatment in a magnetic field can significantly reduce residual stress and improve the structure. The precipitation process is an atomic diffusion process, and the speed of atomic diffusion depends on the diffusion flux. The magnetic field disrupts the equilibrium vacancy concentration, increases the number of vacancies and significantly activates their fluidity, thereby accelerating the diffusion process, promoting uniform organization, and ultimately reducing the residual stress inside the alloy.

[0095] The residual stress calculation process is as follows Figure 2 The residual stress calculation results are shown in Table 1:

[0096] Table 1 Residual stress results of comparative example 1 and embodiments 1 and 2

[0097] Group Residual stress (MPa) Residual stress reduction ratio (%) Comparative Example 1 -144.9 Example 1 9.8 100 Example 2 -50 65 Example 3 10 100 Example 4 -122 15.8 Example 5 -86.5 40 Example 6 -23.1 84 Example 7 -20 86.2 Example 8 -134 7.5 Example 9 2.3 100

[0098] Figure 2 In the nanoindentation load displacement curves of the rolled sample, annealed sample, and alloy sample that was treated with both magnetic field and annealing, the residual stress value of the rolled sample calculated by the nanoindentation model was -144.9 MPa, the annealed sample was only annealed, and its residual stress value was -23.3 MPa, and the alloy sample treated with magnetic field and annealing was annealed while applying a magnetic field to the rolled sample, and its residual stress value was 9.8 MPa. This shows that applying a magnetic field during the annealing process can reduce residual stress.

[0099] Figure 3 Microstructure of the alloy (a) rolled sample (b) simultaneous magnetic field and annealing treatment It can be seen that recovery structure appeared in the alloy sample subjected to simultaneous magnetic field and annealing treatment, which is the main reason for the reduction of its residual stress value.

[0100] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For the ordinary technical personnel in the field, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A pulsed magnetic field treatment method for eliminating residual stress in a copper alloy strip, characterized in that: The following steps are involved: Step 1, alloy melting and casting: under the action of a pulsed magnetic field, the copper alloy material is melted at a temperature of 1000°C to 1300°C to form an alloy melt, which is then poured into a casting mold for cooling and casting to obtain an ingot; Step 2, solution treatment: under the action of a pulsed magnetic field, the ingot is heated and kept warm at a temperature of 800°C to 1350°C for a time of 0.5h to 24h, so that the second phase in the alloy is completely or maximally dissolved into the solid solution matrix; Step 3, hot rolling: hot rolling the solution treated ingot under the action of a pulsed magnetic field; Step 4, cold rolling: cold rolling the copper alloy slab N times under the action of a pulsed magnetic field, where N is any positive integer, until the thickness requirement is met, thereby obtaining a copper alloy thin strip; Step 5, tension annealing: under the action of a pulsed magnetic field, the copper alloy strip is heated and annealed at a temperature of 100°C to 400°C and a holding time of 30s to 12h; a copper alloy strip sample with residual stress eliminated is obtained by combined heat treatment and magnetic field treatment.

2. A pulsed magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: The pulse magnetic field of steps 1 to 5 has a current of 20A to 100000A, a frequency of 20Hz to 100Hz, a duty cycle of 20% to 100%, and a magnetic induction intensity of 0 to M, wherein the M value is implemented according to the specific process, and M is less than the limit met by the instrument.

3. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: During the solution treatment in step S2, inert gas is continuously introduced to prevent oxidation of the copper alloy ingot.

4. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: The time interval for hot rolling the solution treated ingot shall not exceed 30s.

5. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: The plate should be pickled before and after step S3 and step S4 to remove oxide scale and impurities to ensure the surface quality of the product.

6. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: In step 4, intermediate annealing is performed in the cold rolling gap of N cold rollings to reduce the hardness of the alloy and facilitate further cold rolling of the copper alloy slab. The intermediate annealing temperature is 100 to 800° C. and the holding time is 10 minutes to 12 hours.

7. A pulsed magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 6, characterized in that: In step 4, the number of cold rolling passes is 10 to 30.

8. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: In step 5, the pulse magnetic field and heating annealing are carried out simultaneously or before or after the pulse magnetic field treatment, and the residual stress inside the alloy is reduced and the alloy properties are improved through the combined effects of the magnetic field, thermal field and force.

9. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy strip according to claim 1, characterized in that: The direction of the magnetic field should be controlled during the treatment of the pulsed magnetic field.

10. The pulse magnetic field treatment method for eliminating residual stress in a copper alloy thin strip according to claim 1, characterized in that: The copper alloy material is Cu-Fe copper alloy, Cu-Cr copper alloy and Cu-Ni copper alloy.

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