Preparation method of high-performance metal flat belt

Abstract

The invention relates to the field of high-performance bonding materials for packaging, and particularly discloses a preparation method of a high-performance metal flat ribbon, which comprises the following steps: S1, heating a metal raw material with the purity of greater than or equal to 99.999% to a melting point, and smelting to obtain a metal solution; s2, the metal solution passes through a crystallizer, and is cooled into a single crystal metal wire at the temperature gradient of 100-200 DEG C / cm and the pulling speed of 1-4 mm / h; s3, the single-crystal metal wire is calendered at the reduction rate of 40-60%, and a metal blank strip with the thickness of 15-40 [mu] m is obtained; s4, the metal blank strip is subjected to heat treatment, and the metal flat strip is obtained.The single crystal copper material technology is used in cooperation with the adjusting heat treatment process, the metal flat strip is obtained, coating treatment is conducted on the outer face of the metal flat strip, the tensile strength, reliability and operability of the obtained metal flat strip are high, the electrical resistivity is low, and the performance of the metal flat strip is obviously improved.

Description

Technical Field

[0001] This application relates to the field of high-performance bonding materials for packaging, and more specifically, it relates to a method for preparing a high-performance metal flat strip. Background Technology

[0002] Traditional wire bonding typically uses fine metal wires with a circular cross-section. These wires are available in a wide variety of materials and sizes, and the manufacturing technology is relatively mature, making them widely used in the market. However, their drawbacks and disadvantages have gradually become apparent with further research and application. These include low current carrying capacity, inadequate heat dissipation for high-power packaging, low strength, and poor reliability, making them increasingly difficult to meet the needs of technological advancements.

[0003] Bonded metal strips have advantages such as high strength, large current carrying capacity, and good heat dissipation performance, which can meet the needs of microwave and high-power devices. Moreover, due to the difference in bonding methods, the bonding strip has a larger connection area with the substrate during bonding, which can provide a more reliable connection effect.

[0004] Roller rolling has advantages in the preparation of metal strips, such as simple preparation process, high production efficiency and high dimensional accuracy. The characteristics of the metal strip produced by rolling are: the upper and lower thickness surfaces are parallel, and the two sides of the metal strip bulge outward to form a drum shape in cross section. Because its shape is like a thin strip, it is also called metal flat strip or metal flat wire. It has the characteristics of large heat dissipation area, wide contact area, high tensile strength and moderate hardness, and is used in bonding materials and some special fields.

[0005] However, the internal stress distribution and existence form of rolled metal strips are relatively complex. Their surface is prone to unevenness, deformation, cracking and other phenomena. In addition, excessive residual stress can cause the strip to warp, deform and burr. This results in uneven performance and decreased stability of the metal strip, which cannot meet the packaging requirements of high-performance devices. Summary of the Invention

[0006] In order to overcome the defects of uneven quality and decreased stability of the metal flat strip mentioned above, and to improve the performance of the metal flat strip, this application provides a method for preparing high-performance metal flat strip.

[0007] A method for preparing a high-performance metal flat strip includes the following steps: S1: Heat metal raw materials with a purity ≥ 99.999% to their melting point to obtain a metal solution; S2: The metal solution is passed through a crystallizer and cooled into a single crystal metal wire at a temperature gradient of 100-200℃ / cm and a pulling speed of 1-4mm / h. S3: Roll the single crystal metal wire with a reduction rate of 40-60% to obtain a metal blank strip with a thickness of 15-40μm; S4: Heat treat the metal billet strip to obtain a flat metal strip.

[0008] By adopting the above technical solution, metal raw materials with a purity ≥99.999% are heated to their melting point to obtain a molten metal solution, which is beneficial for removing impurities and oxides, thus obtaining a high-purity molten metal solution. Then, using single-crystal copper material technology, the molten metal solution is passed through a crystallizer and cooled at a temperature gradient of 100-200℃ / cm and a pulling speed of 1-4mm / h to solidify the molten metal solution into a single-crystal metal wire. The single-crystal structure is beneficial for improving the mechanical and electrical properties of the metal. Then, the single-crystal metal wire is rolled at a reduction rate of 40-60%, which allows the single-crystal metal wire to undergo plastic deformation during the rolling process, resulting in a metal billet strip with a thickness of 15-40μm. Finally, the metal billet strip is heat-treated to eliminate the stress and grain boundary deformation generated during the rolling process, while adjusting the grain structure and mechanical properties of the metal, ultimately obtaining the desired metal flat strip.

[0009] Preferably, the metal raw material in S1 is any one of copper, aluminum, and gold.

[0010] Copper and gold possess excellent electrical conductivity; therefore, using copper or gold in the fabrication of metal strips can improve their conductivity, making them more suitable for applications requiring good conductivity. Aluminum exhibits good corrosion resistance; using aluminum as a raw material can enhance the corrosion resistance of metal strips and extend their service life. Aluminum is a lightweight metal; using aluminum as a raw material results in lighter metal strips, suitable for applications with high weight reduction requirements. Therefore, appropriate metal raw materials can be selected to fabricate metal strips based on specific application needs.

[0011] Preferably, the annealing temperature for heat treatment in S4 is 300-700℃.

[0012] By adopting the above technical solution, annealing at a temperature range of 300-700℃ during the preparation of metal flat strips can promote the recrystallization of metal grains, thereby eliminating the stress and deformation generated during the rolling process and adjusting the grain size. It can also effectively eliminate the internal stress generated during the processing of metal flat strips, improve the grain structure and properties of metal flat strips, and enhance their performance.

[0013] Preferably, the annealing rate of the heat treatment in S4 is 15-35 m / min.

[0014] By adopting the above technical solution, adjusting the annealing speed of heat treatment to 15-35 m / min during the preparation of metal strips can help the grains grow more uniformly and finely. It can also ensure that the metal strips receive uniform cooling during annealing, avoid generating excessive temperature gradients and thermal stress, thereby reducing deformation and cracks in the metal during annealing, improving the microstructure of the metal strips, and giving them better comprehensive performance.

[0015] Preferably, the annealing tension during the heat treatment in S4 is 3-5g.

[0016] By adopting the above technical solution, adjusting the annealing tension of the heat treatment to 3-5g during the preparation of metal flat strips can help control the growth of metal grains, enabling them to be uniformly refined during annealing. This reduces deformation and internal stress in the metal during annealing, and also helps control the dimensional accuracy of the metal flat strips, ensuring stable dimensions and shapes during processing, reducing processing errors and waste, and improving product uniformity and stability. Simultaneously, it can improve the surface quality of the metal flat strips, reduce surface defects and oxidation, improve the microstructure of the metal flat strips, and enhance dimensional accuracy and surface quality, thereby improving its overall performance and stability.

[0017] Preferably, the method for preparing the high-performance metal flat strip further includes a surface coating treatment step on the metal flat strip obtained in S4.

[0018] By employing the above technical solution, a composite metal strip can be obtained by surface coating a metal strip. The surface coating can impart superior properties not found in single-metal strips. The coating can improve the surface properties of the metal strip, such as increasing hardness, wear resistance, and fatigue resistance, thereby improving the metal's service life and stability. It can also improve the electrical and thermal conductivity of the metal strip, making it more suitable for applications in electronic devices and heat conduction fields. Furthermore, the coating can improve the surface finish and smoothness of the metal strip, enhancing its overall quality performance.

[0019] Preferably, the surface coating treatment is magnetron sputtering. The specific operation of magnetron sputtering is as follows: under vacuum conditions, the metal strip is heated, and then the metal is sprayed onto the metal strip at a sputtering power of 0.8-1 kW and a sputtering time of 10-50 min. Magnetron sputtering is a commonly used surface coating method. In magnetron sputtering, by controlling a magnetic field, metal atoms on the surface of the metal target are bombarded by ions and sputtered, depositing on the surface of the metal strip. By heating the metal strip and applying sputtering power, the metal atoms gain sufficient kinetic energy after being bombarded by ions, thus overcoming surface tension and diffusion resistance, and depositing on the surface of the metal strip.

[0020] In this application, by adopting the above-mentioned technical solution, controlling the sputtering power to be 0.8-1 kW and the sputtering time to be 10-50 min, a uniform coating can be applied to the surface of the metal strip, ensuring that the thickness and composition of the coating are evenly distributed. Precise control of the thickness and composition of the coating results in a high bonding strength between the coating and the metal strip, with good adhesion and stability, thereby improving the performance of the composite metal strip, effectively improving the high-temperature strength, stability and reliability of the bonded metal strip, and increasing the connection strength between the metal interfaces during the bonding process.

[0021] Preferably, the sprayed metal is any one of Au, Ag, and Pd.

[0022] By adopting the above technical solution, in the metal strip manufacturing process, the coating can be any one of Au, Ag, and Pd. Gold, silver, and palladium all have good corrosion resistance, so coating the surface of the metal strip with these metals can improve its corrosion resistance and extend its service life. Gold, silver, and palladium are all good conductive materials, and the coating can improve the conductivity of the metal strip, making it more suitable for applications requiring good conductivity. Gold, silver, and palladium all have good oxidation resistance, and the coating can improve the oxidation resistance of the metal strip, making it more suitable for applications in high-temperature environments. In addition, Au, Ag, and Pd are all precious metals, and using them in the coating can reduce their usage, effectively reducing the cost of the metal strip while improving the performance of the composite metal strip.

[0023] In summary, this application includes at least one of the following beneficial technical effects: This application obtains high-performance metal flat strips by adjusting various process parameters in the metal flat strip preparation process.

[0024] This application improves the performance of metal flat strips by adjusting the process parameters of heat treatment during the preparation of metal flat strips.

[0025] This application improves the performance of metal flat strips by coating the outside of the metal flat strip to form a composite metal flat strip.

[0026] Therefore, this application obtains metal flat strips by adjusting various process parameters in the metal flat strip preparation process, using single crystal copper material technology, and coordinating with the heat treatment process, and then coating the outside of the strips. This results in metal flat strips with a maximum tensile strength of 257 MPa, reliability of 504 PC and workability of 99 UPH, and a minimum resistivity of 1.34 µΩ / cm, which significantly improves the performance of the metal flat strips. Detailed Implementation

[0027] The present application will be further described in detail below with reference to specific embodiments.

[0028] All the following raw materials mentioned in this application are commercially available products and are intended to fully disclose the raw materials in this application. They should not be construed as limiting the source of the raw materials. Example

[0029] The following are experimental examples of copper metal flat strips: Example 1

[0030] The copper metal flat strip of Example 1 was prepared by the following method: S1: Heat copper raw material with a purity of 99.999% to its melting point to obtain copper metal solution; S2: The metal solution is passed through a crystallizer and cooled into a single crystal copper wire under a temperature gradient of 100℃ / cm and a pulling speed of 4mm / h. S3: Roll the single crystal metal wire with a reduction rate of 40% to obtain a copper metal strip with a thickness of 40μm; S4: The metal billet strip is heat-treated, wherein the annealing temperature is 250℃, the speed is 12m / min, and the tension is 2.5g to obtain a copper metal flat strip.

[0031] Example 1.1 The preparation method of the high-performance copper metal flat strip in Example 1.1 is the same as that in Example 1, except that the temperature gradient of the crystallizer in S2 is 200℃ / cm.

[0032] Example 1.2 The preparation method of the high-performance copper metal flat strip in Example 1.2 is the same as that in Example 1, except that the pulling speed of the crystallizer in S2 is 1 mm / h.

[0033] Example 1.3 The preparation method of the high-performance copper metal flat strip in Example 1.3 is the same as that in Example 1, except that the reduction rate in S3 is 60%, and a copper metal blank strip with a thickness of 15μm is obtained.

[0034] Example 1.4 The preparation method of the high-performance copper metal flat strip in Example 1.4 is the same as that in Example 1, except that the annealing temperature of heat treatment in S4 is 300°C.

[0035] Example 1.5 The preparation method of the high-performance copper metal flat strip in Example 1.5 is the same as that in Example 1, except that the annealing temperature of heat treatment in S4 is 700℃.

[0036] Example 1.6 The preparation method of the high-performance copper metal flat strip in Example 1.6 is the same as that in Example 1, except that the annealing rate of heat treatment in S4 is 15m / min.

[0037] Example 1.7 The preparation method of the high-performance copper metal flat strip in Example 1.7 is the same as that in Example 1, except that the annealing rate of heat treatment in S4 is 35 m / min.

[0038] Example 1.8 The preparation method of the high-performance copper metal flat strip in Example 1.8 is the same as that in Example 1, except that the annealing tension in heat treatment S4 is 3g.

[0039] Example 1.9 The preparation method of the high-performance copper metal flat strip in Example 1.9 is the same as that in Example 1, except that the annealing tension in heat treatment in S4 is 5g. Example 2

[0040] The preparation method of the high-performance metal flat strip in Example 2 is the same as that in Example 1, except that the metal raw material used in S1 is aluminum raw material with a purity of 99.999%, and the prepared material is aluminum metal flat strip. Example 3

[0041] The preparation method of the high-performance metal flat strip in Example 3 is the same as that in Example 1, except that the metal raw material used in S1 is gold with a purity of 99.999%, and the prepared metal flat strip is gold.

[0042] The following are experimental examples of composite metal flat strips: Example 4

[0043] The composite metal flat strip of Example 4 was prepared by the following steps: The copper metal strip prepared in Example 1 was subjected to surface coating treatment. The specific method is as follows: Under vacuum conditions, the copper metal strip was heated to 200°C, and then sputtered at a sputtering power of 0.75 kW for 50 minutes to spray metal Ag onto the copper metal strip to obtain Cu-Ag composite metal strip.

[0044] Example 4.1 The composite metal flat strip of Example 4.1 was prepared by the following steps: The copper metal strip prepared in Example 4.1 was subjected to surface coating treatment. The specific method is as follows: Under vacuum conditions, the copper metal strip was heated to 200°C, and then sputtered with a sputtering power of 1 kW for 10 min to spray metal Ag onto the metal strip to obtain Cu-Ag composite metal strip. Example 5

[0045] The preparation method of the high-performance metal flat strip of the composite material in Example 5 is the same as that in Example 4, except that the metal sprayed is Au, and Cu-Au composite metal flat strip is prepared. Example 6

[0046] The preparation method of the high-performance metal flat strip of the composite material in Example 6 is the same as that in Example 4, except that the metal sprayed is Pd, and a Cu-Pd composite metal flat strip is prepared. Example 7

[0047] The preparation method of the high-performance metal flat strip of the composite material in Example 7 is the same as that in Example 4, except that the aluminum metal flat strip prepared in Example 2 is used to prepare the Al-Ag composite metal flat strip. Example 8

[0048] The preparation method of the high-performance metal flat strip of the composite material in Example 8 is the same as that in Example 4, except that the metal flat strip is the gold metal flat strip prepared in Example 3, and Au-Ag composite metal flat strip is obtained. Comparative Example

[0049] Comparative Example 1 The preparation method of the high-performance copper metal flat strip in Comparative Example 1 is the same as that in Example 1, except that the temperature gradient of the crystallizer in S2 is 80℃ / cm.

[0050] Comparative Example 2 The preparation method of the high-performance copper metal flat strip in Comparative Example 2 is the same as that in Example 1, except that the temperature gradient of the crystallizer in S2 is 220℃ / cm.

[0051] Comparative Example 3 The preparation method of the high-performance copper metal flat strip in Comparative Example 3 is the same as that in Example 1, except that the pulling speed of the crystallizer in S2 is 0.5 mm / h.

[0052] Comparative Example 4 The preparation method of the high-performance copper metal flat strip in Comparative Example 4 is the same as that in Example 1, except that the pulling speed of the crystallizer in S2 is 4.5 mm / h.

[0053] Comparative Example 5 The preparation method of the high-performance copper metal flat strip in Comparative Example 5 is the same as that in Example 1, except that the reduction rate in S3 is 35%.

[0054] Comparative Example 6 The preparation method of the high-performance copper metal flat strip in Comparative Example 6 is the same as that in Example 1, except that the reduction rate in S3 is 65%. Performance testing

[0055] The performance of the metal flat strips obtained by different Examples 1-8 and Comparative Examples 1-6 was tested according to the GB / T34502-2017 standard. The test results are shown in Table 1. The reliability was demonstrated by the fatigue deformation test of the metal flat strip.

[0056] Table 1. Performance test results of different copper metal strips Tensile strength / MPa Reliability (fatigue deformation resistance test) / 10,000 cycles Resistivity / µΩ / cm Operational / UPH Example 1 242 80 1.57 99 Example 1.1 244 81 1.58 99 Example 1.2 245 81 1.56 99 Example 1.3 246 83 1.56 99 Example 1.4 245 83 1.56 99 Example 1.5 248 84 1.39 99 Example 1.6 249 84 1.42 99 Example 1.7 248 84 1.53 99 Example 1.8 248 84 1.56 99 Example 1.9 249 85 1.52 99 Example 2 240 78 1.62 99 Example 3 250 88 1.47 99 Example 4 249 84 1.52 99 Example 4.1 247 83 1.50 99 Example 5 257 84 1.34 99 Example 6 254 88 1.35 99 Example 7 246 83 1.54 99 Example 8 256 84 1.35 99 Comparative Example 1 229 78 1.71 99 Comparative Example 2 227 69 1.66 99 Comparative Example 3 231 70 1.65 99 Comparative Example 4 234 68 1.76 99 Comparative Example 5 219 62 1.82 99 Comparative Example 6 222 60 3.56 99 The test results in Table 1 show that the metal flat strip obtained in this application has the highest tensile strength, reliability, and workability of 257 MPa, 880,000 cycles, and 99 UPH, respectively, and the lowest resistivity of 1.34 µΩ / cm, which significantly improves the performance of the metal flat strip.

[0057] In Examples 1 and 1.4-1.5, the tensile strength and reliability of the copper metal flat strips obtained in Examples 1.4-1.5 are higher than those in Example 1, while the resistivity is lower. This indicates that an annealing temperature of 300-700℃ is more suitable for heat treatment in the preparation of copper metal flat strips, which improves the performance of the copper metal flat strips. This may be related to the fact that adjusting the annealing temperature of heat treatment to 300-700℃ can improve the microstructure of the copper metal flat strips.

[0058] In Examples 1 and 1.6-1.7, the tensile strength and reliability of the copper metal flat strips obtained in Examples 1.6-1.7 are higher than those in Example 1, while the resistivity is lower. This indicates that an annealing rate of 15-35 m / min during the heat treatment of the copper metal flat strip is more suitable, which improves the performance of the copper metal flat strip. This may be related to the fact that adjusting the annealing rate of the heat treatment to 15-35 m / min can improve the microstructure of the copper metal flat strip.

[0059] In Examples 1 and 1.8-1.9, the tensile strength and reliability of the copper metal flat strips obtained in Examples 1.8-1.9 are higher than those in Example 1, while the resistivity is lower. This indicates that an annealing tension of 3-5g during the heat treatment of the copper metal flat strip is more suitable, which improves the performance of the copper metal flat strip. This may be related to the fact that adjusting the annealing tension of the heat treatment to 3-5g can improve the microstructure of the copper metal flat strip.

[0060] Based on the copper metal flat strip obtained in Example 1, the aluminum metal flat strip obtained in Example 2 has a tensile strength, reliability, and workability of 240 MPa, 780,000 cycles, and 99 UPH, respectively, and a resistivity of 1.62 µΩ / cm; the gold metal flat strip obtained in Example 3 has a tensile strength, reliability, and workability of 250 MPa, 880,000 cycles, and 99 UPH, respectively, and a resistivity of 1.47 µΩ / cm. This indicates that when the metal raw material in S1 is any one of copper, aluminum, or gold, a metal flat strip with good performance can be obtained.

[0061] In Examples 1 and 4-4.1, the copper metal strips obtained in Examples 4-4.1 have higher tensile strength and reliability than those in Example 1, and lower resistivity than those in Example 1. This indicates that the preparation method of high-performance metal strips further includes a surface coating treatment step on the metal strips obtained in S4, and the surface coating treatment is adjusted to magnetron sputtering. Specifically, the metal blank strip is heated under vacuum conditions, and then the metal is sprayed onto the metal strip at a sputtering power of 0.8-1 kW and a sputtering time of 10-50 min. This method can improve the adhesion and stability of the metal strips.

[0062] The copper metal flat strips obtained in Examples 5-8 have tensile strength, reliability, and workability of 246-257 MPa, 830,000-880,000 cycles, and 99 UPH, respectively, and resistivity of 1.34-1.54 µΩ / cm, indicating that metal flat strips with good performance can be obtained when the sprayed metal is any one of Au, Ag, and Pd.

[0063] Furthermore, based on the various performance data of the copper metal flat strips in Comparative Examples 1-6 and Examples 1-1.3, it was found that in the production method of copper metal flat strips of this application, adjusting the temperature gradient to 100-200℃ / cm and the pulling speed to 1-4mm / h when preparing single crystal metal wires in step S2, and the reduction rate to 40-60% in step S3, can improve the performance of copper metal flat strips to varying degrees.

[0064] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a high-performance metal flat strip, characterized in that, Includes the following steps: S1: Heat metal raw materials with a purity ≥ 99.999% to their melting point to obtain a metal solution; S2: The metal solution is passed through a crystallizer and cooled into a single crystal metal wire at a temperature gradient of 100-200℃ / cm and a pulling speed of 1-4mm / h. S3: Roll the single crystal metal wire with a reduction rate of 40-60% to obtain a metal blank strip with a thickness of 15-40μm; S4: Heat treat the metal billet strip to obtain a flat metal strip.

2. The method for preparing high-performance metal flat strips according to claim 1, characterized in that, The metal raw material in S1 is any one of copper, aluminum, and gold.

3. The method for preparing high-performance metal flat strips according to claim 1, characterized in that, The annealing temperature for heat treatment in S4 is 300-700℃.

4. The method for preparing high-performance metal flat strips according to claim 1, characterized in that, The annealing rate for heat treatment in S4 is 15-35 m / min.

5. The method for preparing high-performance metal flat strips according to claim 1, characterized in that, The annealing tension during heat treatment in S4 is 3-5g.

6. The method for preparing high-performance metal flat strips according to claim 1, characterized in that, The method further includes a surface coating process for the metal flat strip obtained in S4.

7. The method for preparing high-performance metal flat strips according to claim 6, characterized in that, The surface coating treatment is performed by magnetron sputtering. The specific operation of the magnetron sputtering method is as follows: under vacuum conditions, the metal strip is heated, and then the metal is sprayed onto the metal flat strip at a sputtering power of 0.8-1 kW and a sputtering time of 10-50 min.

8. The method for preparing high-performance metal flat strips according to claim 7, characterized in that, The sprayed metal is any one of Au, Ag, and Pd.