A method of producing high performance copper-based leadframe materials by powder metallurgy

Abstract

The application provides a method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique, and belongs to the field of composite materials.The method comprises the following steps: firstly, mixing carbon nanotubes and a copper-nickel-silicon alloy; then, performing discharge plasma sintering on the mixed powder to obtain a composite block; and finally, performing solid solution treatment, cold rolling and aging treatment on the composite block to obtain a final carbon nanotube / copper-nickel-silicon composite material.In the copper-nickel-silicon alloy, the carbon nanotubes are introduced in a "boiling dispersion" mode, so that the CNTs are uniformly dispersed in the Cu-Ni-Si alloy powder, the migration of the grain boundary can be effectively hindered, the grain growth is inhibited, the electrical and conductive properties of the material are significantly improved, and the defects, such as uneven composition, low density and poor material performance caused in the smelting and casting process, are effectively solved.The method simplifies the preparation process, shortens the preparation time and reduces the production cost, and is a green and environment-friendly preparation mode.

Description

TECHNICAL FIELD

[0001] The application relates to a method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique and belongs to the field of composite materials. BACKGROUND

[0002] The Cu-Ni-Si alloy belongs to a typical age-hardening alloy and is one of main materials for lead frames, and at present, the copper-based lead frame materials widely used at home and abroad have the problem of mismatch between the electrical conductivity and the strength. The traditional smelting and casting technique has the problems of segregation of alloy elements when producing the Cu-Ni-Si alloy, and due to the slow cooling speed of the molten metal, the matrix grain is coarsened (the grain size is as high as 250 mu m), the size of the precipitated phase is large, and the precipitation strengthening effect is reduced. The product performance is adversely affected. In addition, the smelting and casting method has the defects of long process flow, large energy consumption and low product utilization rate.

[0003] The carbon nanotubes (CNTs) are a kind of nanometer reinforcing bodies with excellent mechanical properties, electrical conductivity and thermal conductivity. The introduction of the CNTs is expected to further refine the size of the Ni-Si precipitated phase in the alloy, and meanwhile, the CNTs can hinder the grain boundary migration and prevent the grain growth, so that the strength of the Cu-Ni-Si alloy is improved while the excellent electrical conductivity is maintained. Conventionally, the CNTs are directly added to the molten liquid Cu-Ni-Si alloy, and there are the problems of large density difference between the CNTs and the Cu-Ni-Si alloy, which causes the composition segregation of the material, the uneven dispersion of the CNTs, the large amount of pores and other defects, the low density of the composite material and the brittle fracture of the material, and thus the performance of the material is affected. Therefore, for the development of the high-performance Cu-Ni-Si alloy, a new preparation method and process need to be explored. SUMMARY

[0004] In order to ensure the composition uniformity of the Cu-Ni-Si alloy matrix and further improve the dispersion of the CNTs in the matrix, realize the grain refinement of the alloy, the nanometerization of the precipitated phase and the microstructure homogenization, the application provides a method for preparing a high-strength and high-conductivity Cu-Ni-Si alloy material by a powder metallurgy technique; the CNTs are introduced into the gas-atomized Cu-Ni-Si alloy powder, so that the CNTs are uniformly dispersed in the Cu-Ni-Si powder matrix, and then the CNTs / Cu-Ni-Si composite material is generated through sintering, solid solution, cold rolling and aging treatment. The powder metallurgy technique has remarkable advantages in controlling the size of the material grain and the size of the precipitated phase, so that the electrical performance of the composite material is improved, and the mechanical performance of the material is improved.

[0005] The method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique comprises the following steps:

[0006] (1) Put high-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate into a vacuum induction melting furnace for melting. The Cu-Ni-Si alloy spherical powder with uniform particle size is obtained by ultrasonic atomization technology.

[0007] (2) Put CNTs into anhydrous ethanol for ultrasonic dispersion to obtain a uniformly dispersed CNTs mixture, then pour the Cu-Ni-Si alloy powder into the CNTs mixture for "boiling dispersion" mixing treatment by a rotary evaporator to obtain a uniform CNTs / Cu-Ni-Si mixture, and then dry the mixture by a vacuum drying box to obtain a CNTs / Cu-Ni-Si mixed powder.

[0008] (3) The CNTs / Cu-Ni-Si mixed powder of step (2) is subjected to discharge plasma sintering to obtain a CNTs / Cu-Ni-Si sintered body, and then subjected to high-temperature solid solution treatment to obtain a homogeneous composite block.

[0009] (4) The composite block of step (3) is subjected to multi-pass cold rolling treatment, and finally subjected to aging treatment to obtain a CNTs / Cu-Ni-Si composite material.

[0010] Preferably, the ultrasonic dispersion time of CNTs in anhydrous ethanol in step (2) is 0.5h-2h.

[0011] Preferably, the mass ratio of CNTs / Cu-Ni-Si alloy in step (2) is 0.02g-0.09g:26g.

[0012] Preferably, the specific operation steps of "boiling dispersion" mixing treatment in step (2) are as follows: pour the CNTs mixture and Cu-Ni-Si alloy powder into a round-bottom flask with a vent valve, then install it on a rotary evaporator, open the vacuum pump for vacuumizing, immediately close the vent valve after vacuumizing, then open the rotation switch at a speed of 60r / min-70r / min, and then open the heating switch to make the water bath temperature reach 60℃-80℃, and the holding time is 1h-3h.

[0013] Preferably, the drying temperature in step (2) is 70℃-80℃, and the drying time is 10h-14h.

[0014] Preferably, the discharge plasma sintering temperature in step (3) is 700℃-900℃, the heating rate is (50-200)℃ / min, and the holding time is 5min-20min.

[0015] Preferably, the temperature of the solution treatment in step (3) is 800° C. to 1000° C., the time of the solution treatment is 0.5 h to 2 h, and cooling is performed by water quenching.

[0016] Preferably, the temperature of the cold rolling treatment in step (4) is 150° C. to 300° C., the number of rolling passes is 3 to 6 times, and the rolling amount of each pass is 1 mm to 2 mm.

[0017] Preferably, the aging treatment temperature in step (4) is 350° C. to 550° C., the aging treatment time is 2 h to 8 h, and cooling is performed by water quenching.

[0018] Advantageous Effects of the Invention

[0019] (1) The powder metallurgy route used in the present invention can obtain a homogeneous composite block (structure, composition) with a high density, avoiding the phenomenon of component segregation and coarse casting structure during smelting and casting.

[0020] (2) The present invention can effectively hinder the migration of grain boundaries and thus inhibit grain growth by introducing CNTs; it also has the effect of refining the precipitated phase, so that the electrical and conductive properties of the prepared material are significantly improved.

[0021] (3) The present invention adopts the method of "boiling dispersion" to introduce CNTs into Cu-Ni-Si alloy powder, so that CNTs are evenly dispersed in the Cu-Ni-Si alloy powder, effectively solving the defects such as uneven composition and low density resulting in poor material performance during the smelting and casting process.

[0022] (4) The method of the present invention simplifies the preparation process, shortens the preparation time, and reduces the production cost. At the same time, the invention is a green and environmentally friendly preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the powder SEM image of Cu-Ni-Si alloy material.

[0024] Figure 2 This is a metallographic micrograph of the CNTs / Cu-Ni-Si composite material in Example 1.

[0025] Figure 3 This is the SEM image of the CNTs / Cu-Ni-Si composite powder in Example 2.

[0026] Figure 4 This is the SEM image of the CNTs / Cu-Ni-Si composite material in Example 3.

[0027] Figure 5 This is the TEM image of the CNTs / Cu-Ni-Si composite material in Example 2.

[0028] Figure 6 Stress-strain curves of Cu-Ni-Si alloy strips and composite materials obtained in each example. DETAILED DESCRIPTION

[0029] Hereinafter, the technical solutions of the present application are described in detail through specific examples.

[0030] Example 1

[0031] A method for preparing high-performance copper-based lead frame material by a powder metallurgy technology, comprising the following steps:

[0032] (1) Put high-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate into a vacuum induction melting furnace for melting, and atomize them into spherical copper-nickel-silicon alloy powder with uniform particle size by ultrasonic atomization technology.

[0033] (2) Add 0.087 g of CNTs to 150 mL of anhydrous ethanol solution, and ultrasonically disperse for 60 min in an ultrasonic machine with a power of 300 W to obtain a uniformly dispersed CNTs mixed solution. Put the CNTs mixed solution and 26 g of Cu-Ni-Si alloy powder into a rotary evaporator and rotate and boil at 60 r / min and 70℃ for 2 h, and then dry in a vacuum drying box at 70℃ for 10 h, to finally obtain 26 g of dry CNTs / Cu-Ni-Si mixed powder.

[0034] (3) Put 17 g of CNTs / Cu-Ni-Si mixed powder in (2) into a graphite mold with a diameter of 20 mm for 15 MPa pre-pressing for 3 min, and then discharge plasma sintering, with a sintering temperature of 900℃, a heating rate of 100℃ / min and a holding time of 5 min, to obtain a 6 mm thick CNTs / Cu-Ni-Si sintered compact; and then perform 950℃ solid solution treatment for 1 h to obtain a homogeneous composite block.

[0035] (4) Perform 270℃ cold rolling treatment on the composite block in (3), with an opening temperature of 270℃ and a holding time of 10 min, and a total of three passes of rolling, with a downward displacement of 1.5 mm for each pass, to obtain a 1.5 mm thick strip blank; and finally perform aging treatment, with an aging treatment temperature of 450℃ and an aging treatment time of 4 h. Finally, a CNTs / Cu-Ni-Si composite material is obtained.

[0036] The material prepared in this example is subjected to tensile property test.

[0037] The conductivity and hardness of the CNTs / Cu-Ni-Si composite material obtained in this example are shown in Table 1. The conductivity of the CNTs / Cu-Ni-Si composite material obtained in this example is increased by 53% and the hardness is increased by 29% compared with the CNTs / Cu-Ni-Si composite material obtained in Comparative Example 2.

[0038] The metallographic image of the CNTs / Cu-Ni-Si composite material obtained in this example is shown in Figure 1. Compared with the Cu-Ni-Si alloy, the size of the grains of the CNTs / Cu-Ni-Si composite material is refined to a certain extent, so that the performance of the material is improved. Figure 2

[0039] The stress-strain curve of the CNTs / Cu-Ni-Si composite material obtained in this example is shown in Figure 2. The maximum tensile strength of the CNTs / Cu-Ni-Si composite material obtained in this example is increased by 38% compared with the CNTs / Cu-Ni-Si composite material obtained in Comparative Example 2. Figure 6

[0040] Example 2

[0041] A method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique, comprising the following steps:

[0042] (1) Put high-purity electrolytic Cu plates, high-purity electrolytic Ni plates and high-purity electrolytic Si plates into a vacuum induction melting furnace for melting, and atomize them into spherical copper-nickel-silicon alloy powder with uniform particle size by ultrasonic atomization technology.

[0043] (2) Add 0.06 g of CNTs to 150 mL of anhydrous ethanol solution and ultrasonically disperse for 1 h in an ultrasonic machine with a power of 300 W to obtain a uniformly dispersed CNTs mixed solution. Pour the CNTs mixed solution and 26 g of Cu-Ni-Si alloy powder into a round-bottom flask with a vent valve, mix them, then install the flask on a rotary evaporator, open the vacuum pump for vacuumizing, immediately close the vent valve after vacuumizing, then open the rotation switch at a speed of 65 r / min, and open the heating switch to make the temperature of the water bath reach 70°C, and keep the temperature for 2 h. Then dry the mixture in a vacuum drying box at 70°C for 12 h to obtain 26 g of dried CNTs / Cu-Ni-Si mixed powder.

[0044] ​​(3) 17 g of the CNTs / Cu-Ni-Si mixed powder in (2) was put into a graphite mold with a diameter of 20 mm for 15 MPa pre-pressing for 3 min, and then was subjected to spark plasma sintering, with a sintering temperature of 800 ℃, a heating rate of 150 ℃ / min, and a holding time of 15 min, to obtain a 6 mm thick CNTs / Cu-Ni-Si sintered compact; then the sintered compact was subjected to 950 ℃ solid solution treatment for 1 h to obtain a homogeneous composite block.

[0045] (4) The composite block in (3) was subjected to 270 ℃ cold rolling treatment, with an opening temperature of 270 ℃ and a holding time of 10 min, and was subjected to a total of four passes of rolling, with a 1.5 mm downward displacement in each pass, to obtain a 1.5 mm thick strip; finally, the strip was subjected to aging treatment, with an aging treatment temperature of 450 ℃ and an aging treatment time of 4 h. Finally, the CNTs / Cu-Ni-Si composite material was obtained.

[0046] The material prepared in this example was subjected to tensile property testing.

[0047] The electrical conductivity and hardness of the CNTs / Cu-Ni-Si composite material obtained in this example 2 are shown in Table 1. The electrical conductivity of the obtained CNTs / Cu-Ni-Si composite material was improved by 23% compared with the Cu-Ni-Si alloy in Comparative Example 1, and the hardness was improved by 21%.

[0048] The SEM of the micro-morphology of the composite material powder obtained in this example 2 is shown in Figure 3 It can be found that the CNTs are uniformly dispersed on the Cu-Ni-Si alloy matrix powder, which is beneficial to the subsequent sintering metallurgical bonding and does not reduce the density of the material, so that the material is more uniform, thereby obtaining more excellent performance.

[0049] The TEM of the CNTs / Cu-Ni-Si composite material obtained in this example 2 is shown in Figure 5 It can be clearly seen that a large amount of CNTs exist, which indicates that the introduction of CNTs effectively inhibits the grain growth, thereby improving the performance of the material.

[0050] The stress-strain curve of the CNTs / Cu-Ni-Si composite material obtained in this example 2 is shown in Figure 6 The maximum tensile strength of the obtained CNTs / Cu-Ni-Si composite material was improved by 42% compared with the Cu-Ni-Si alloy in Comparative Example 1.

[0051] Example 3

[0052] A method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique, prepared by the following steps:

[0053] (1) Put high-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate into a vacuum induction melting furnace for melting, and atomize them into spherical Cu-Ni-Si alloy powder with uniform particle size by ultrasonic atomization technology.

[0054] (2) Add 0.02 g of CNTs to 150 mL of anhydrous ethanol solution, and ultrasonically disperse for 30 min in an ultrasonic machine with a power of 300 W to obtain a uniformly dispersed CNTs mixed solution. Pour the CNTs mixed solution and 26 g of Cu-Ni-Si alloy powder into a round-bottom flask with a vent valve, mix them, then install the flask on a rotary evaporator, open the vacuum pump for vacuumizing, immediately close the vent valve after vacuumizing, then open the rotation switch at a speed of 60 r / min, and open the heating switch to make the temperature of the water bath reach 60℃, and keep the temperature for 1 h. Then dry the mixture in a vacuum drying box at 70℃ for 10 h, and finally obtain 26 g of dried CNTs / Cu-Ni-Si mixed powder.

[0055] (3) Put 17 g of the CNTs / Cu-Ni-Si mixed powder in (2) into a graphite mold with a diameter of 20 mm for pre-pressing at 15 MPa for 3 min, and then perform discharge plasma sintering at a sintering temperature of 700℃ and a heating rate of 50℃ / min, and keep the temperature for 5 min to obtain a 6 mm thick CNTs / Cu-Ni-Si sintered compact; then perform solid solution treatment at 800℃ for 0.5 h to obtain a homogeneous composite block.

[0056] (4) Perform cold rolling treatment on the composite block in (3) at 150℃, with an opening temperature of 150℃ and a holding time of 10 min, and perform a total of 3 passes of rolling, with a downward displacement of 1 mm for each pass, to obtain a 1 mm thick strip; finally perform aging treatment at an aging temperature of 350℃ and an aging time of 2 h. Finally, the CNTs / Cu-Ni-Si composite material is obtained.

[0057] The material prepared in this example is subjected to tensile property testing.

[0058] The electrical conductivity and hardness of the CNTs / Cu-Ni-Si composite material obtained in this example 3 are shown in Table 1. The electrical conductivity of the obtained CNTs / Cu-Ni-Si composite material is increased by 17% and the hardness is increased by 15% compared with the Cu-Ni-Si alloy in Comparative Example 1.

[0059] The SEM image of the CNTs / Cu-Ni-Si composite material obtained in this example 3 is shown in Figure 4 It can be seen that the CNTs are uniformly distributed in the CNTs / Cu-Ni-Si composite material, and can effectively act as a bridge for load transfer, thereby improving the mechanical properties of the material.

[0060] The stress-strain curve of the CNTs / Cu-Ni-Si composite material obtained in this Example 3 is shown in Figure 3, and the maximum tensile strength of the obtained CNTs / Cu-Ni-Si composite material is increased by 33.3% compared with the Cu-Ni-Si alloy in Comparative Example 1. Figure 6 The stress-strain curve of the CNTs / Cu-Ni-Si composite material obtained in this Example 3 is shown in Figure 3, and the maximum tensile strength of the obtained CNTs / Cu-Ni-Si composite material is increased by 33.3% compared with the Cu-Ni-Si alloy in Comparative Example 1.

[0061] Example 4

[0062] A method for preparing a high-performance copper-based lead frame material by a powder metallurgy technique, comprising the following steps:

[0063] (1) Put high-purity electrolytic Cu plates, high-purity electrolytic Ni plates, and high-purity electrolytic Si plates into a vacuum induction melting furnace for melting, and atomize them into spherical copper-nickel-silicon alloy powder with uniform particle size by ultrasonic atomization technology.

[0064] (2) Add 0.09 g of CNTs to 150 mL of anhydrous ethanol solution and ultrasonically disperse for 2 h in an ultrasonic machine with a power of 300 W to obtain a uniformly dispersed CNTs mixed solution. Pour the CNTs mixed solution and 26 g of Cu-Ni-Si alloy powder into a round-bottom flask with a vent valve, mix them, then install the flask on a rotary evaporator, open the vacuum pump for vacuumizing, immediately close the vent valve after vacuumizing, then open the rotation switch at a speed of 70 r / min, and open the heating switch to make the temperature of the water bath reach 80°C, and keep the temperature for 3 h. Then dry the mixture in a vacuum drying box at 80°C for 14 h, and finally obtain 26 g of dried CNTs / Cu-Ni-Si mixed powder.

[0065] (3) Take 17 g of the CNTs / Cu-Ni-Si mixed powder in (2) and put it into a graphite mold with a diameter of 20 mm for pre-pressing at 15 MPa for 3 min, and then perform discharge plasma sintering at a sintering temperature of 900°C and a heating rate of 200°C / min, and keep the temperature for 20 min to obtain a 6 mm thick CNTs / Cu-Ni-Si sintered compact; then perform solid solution treatment at 1000°C for 2 h to obtain a homogeneous composite block.

[0066] (4) Perform cold rolling treatment on the composite block in (3) at 300°C, with an opening temperature of 300°C and a holding time of 10 min, and perform a total of 6 passes of rolling, with a downward displacement of 2 mm for each pass, to obtain a 2 mm thick strip; finally perform aging treatment at an aging temperature of 550°C for an aging time of 8 h. Finally, the CNTs / Cu-Ni-Si composite material is obtained.

[0067] The electrical conductivity and hardness of the CNTs / Cu-Ni-Si composite material obtained in this embodiment are shown in Table 1. The electrical conductivity of the CNTs / Cu-Ni-Si composite material obtained is increased by 50% and the hardness is increased by 30% compared with the CNTs / Cu-Ni-Si composite material obtained in Comparative Example 2.

[0068] Comparative Example 1

[0069] Based on Example 1, except that CNTs were not mixed into the Cu-Ni-Si alloy powder, the other process steps remained unchanged. The specific steps are as follows:

[0070] (1) High-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate are placed in a vacuum induction melting furnace for melting, and are atomized into copper-nickel-silicon alloy spherical powder with uniform particle size by ultrasonic atomization technology.

[0071] (2) 17 g of the Cu-Ni-Si alloy powder in (1) was placed in a graphite mold with a diameter of 20 mm and pre-pressed at 15 MPa for 3 min. Spark plasma sintering was then performed at a sintering temperature of 900 °C, a heating rate of 100 °C / min, and a holding time of 5 min to obtain a 6 mm thick Cu-Ni-Si sintered body. Solution treatment was then performed at 950 °C for 1 h to obtain a homogeneous block.

[0072] (3) The block in (2) was cold rolled at 270°C with a gate opening temperature of 270°C and a holding time of 10 min. A total of three rolling passes were performed, with a reduction of 1.5 mm in each pass, to obtain a 1.5 mm thick strip. Finally, an aging treatment was performed at a temperature of 450°C and a time of 4 h. Finally, a Cu-Ni-Si alloy material was obtained.

[0073] The material prepared in this comparative example was subjected to a tensile property test.

[0074] Figure 1 This is the powder SEM image of Cu-Ni-Si alloy material.

[0075] The electrical conductivity and hardness of the Cu-Ni-Si alloy material obtained in this comparative example are shown in Table 1.

[0076] The stress-strain curve of the Cu-Ni-Si alloy material obtained in this comparative example is shown in FIG. Figure 6 shown.

[0077] Comparative Example 2

[0078] Based on Example 1, a casting and melting method was used to prepare a CNTs / Cu-Ni-Si composite material. The specific steps are as follows:

[0079] (1) Put high-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate into a vacuum induction melting furnace to melt, and obtain a molten Cu-Ni-Si alloy.

[0080] (2) Pour the CNTs dispersion liquid into the molten Cu-Ni-Si alloy, stir thoroughly, and cast into a 120 mm (length) x 65 mm (width) x 25 mm (thickness) ingot.

[0081] (3) Process the ingot in (2) into a 100 mm x 60 mm x 20 mm initial blank, homogenize the initial blank at 950°C for 2 hours, and obtain a homogenized composite block.

[0082] (4) Hot-rolling the composite block in (3) at 950°C to a thickness of 10 mm, then performing 900°C solid solution treatment for 2h, and obtaining a solid solution state composite block.

[0083] (5) Cold-rolling the composite block in (4) at 270°C, with a starting temperature of 270°C and a holding time of 10 min, a total of three passes of rolling, with a 1.5 mm reduction in each pass, to obtain a 1.5 mm thick strip blank; finally, performing aging treatment at a temperature of 450°C for 4h. Finally, obtain the CNTs / Cu-Ni-Si composite material.

[0084] The material prepared in the present example was subjected to tensile property testing.

[0085] The electrical conductivity and hardness of the CNTs / Cu-Ni-Si alloy material obtained in the present example are shown in Table 1.

[0086] The stress-strain curve of the CNTs / Cu-Ni-Si alloy material obtained in the present example is shown in Figure 6 .

[0087] Example 3

[0088] On the basis of Example 2, except that CNTs are not added to the molten Cu-Ni-Si alloy, the remaining steps are unchanged, and the specific steps are as follows:

[0089] (1) Put high-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate into a vacuum induction melting furnace to melt, and obtain a molten Cu-Ni-Si alloy, then cast into a 120 mm (length) x 65 mm (width) x 25 mm (thickness) ingot.

[0090] (2) Process the ingot in (1) into a 100 mm x 60 mm x 20 mm initial blank, homogenize the initial blank at 950°C for 2 hours, and obtain a homogenized block.

[0091] (3) Hot-rolling the block in (2) at 950°C to a block with a thickness of 10 mm, and then performing 900°C solid solution treatment for 2 h to obtain a solid solution state block.

[0092] (4) Cold-rolling the block in (3) at 270°C, with an opening temperature of 270°C and a holding time of 10 min, and a total of three passes of rolling, with a reduction of 1.5 mm per pass, to obtain a strip blank with a thickness of 1.5 mm; and finally performing aging treatment at a temperature of 450°C for 4 h. The Cu-Ni-Si alloy material is finally obtained.

[0093] The material obtained in the present comparative example was subjected to tensile property testing.

[0094] The electrical conductivity and hardness of the Cu-Ni-Si alloy material obtained in the present comparative example are shown in Table 1.

[0095] The stress-strain curve of the Cu-Ni-Si alloy material obtained in the present comparative example is shown in Figure 6 .

[0096] Compared with the Cu-Ni-Si alloy prepared in Comparative Example 1, the hardness of the CNTs / Cu-Ni-Si composite material prepared in Examples 1-4 is greatly improved, and the electrical conductivity is also improved to varying degrees; compared with the CNTs / Cu-Ni-Si alloy prepared by melting and casting in Comparative Example 2, the hardness and electrical conductivity of the CNTs / Cu-Ni-Si composite material prepared in Examples 1-4 are significantly improved; compared with the Cu-Ni-Si alloy prepared by melting and casting in Comparative Example 3, the Cu-Ni-Si alloy prepared by powder metallurgy in Comparative Example 1 has higher hardness and electrical conductivity. This shows that the powder metallurgy method is beneficial to improving the dispersion of CNTs in the Cu-Ni-Si alloy, making the composition more uniform, and making the material obtain higher density, thereby improving the performance of the material; the composite material prepared in Examples 1-4 has the enhancement of CNTs, which improves the tensile strength and electrical conductivity of the material. Further, due to the introduction of CNTs, CNTs effectively hinder the migration of grain boundaries and thus inhibit grain growth; at the same time, it also has the effect of refining precipitated phases, which makes the mechanical and electrical properties of the composite material improve to varying degrees. Therefore, the CNTs / Cu-Ni-Si composite material prepared in Examples 1-4 has good electrical conductivity and high tensile strength.

[0097] Table 1

[0098]

Claims

1. A method for preparing high-performance copper-based lead frame materials using powder metallurgy technology, characterized in that ； (1) High-purity electrolytic Cu plate, high-purity electrolytic Ni plate and high-purity electrolytic Si plate are placed in a vacuum induction melting furnace for smelting, and then atomized into copper-nickel-silicon alloy spherical powder with uniform particle size by ultrasonic atomization technology; (2) CNTs were ultrasonically dispersed in anhydrous ethanol to obtain a uniformly dispersed CNTs mixture, and then Cu-Ni-Si alloy powder was poured into the CNTs mixture. The mixture was subjected to a "boiling dispersion" mixing treatment by a rotary evaporator at a speed of 60-70 r / min and a water bath temperature of 60-80°C for 1-3 h to obtain a uniform CNTs / Cu-Ni-Si mixture. The mixture was then dried in a vacuum drying oven to obtain a CNTs / Cu-Ni-Si mixed powder; wherein the mass ratio of CNTs / Cu-Ni-Si alloy was 0.02 g~0.09 g:26 g; (3) spark plasma sintering the CNTs / Cu-Ni-Si mixed powder of step (2) at a sintering heating rate of 50-200°C / min to obtain a CNTs / Cu-Ni-Si sintered body, and then performing a high-temperature solution treatment to obtain a homogeneous composite block; (4) The composite block of step (3) is subjected to multiple cold rolling processes at a rolling temperature of 150-300°C, and finally subjected to aging treatment to obtain a CNTs / Cu-Ni-Si composite material.

2. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (2), the ultrasonic dispersion time of CNTs in anhydrous ethanol is 0.5 h~2 h.

3. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: The specific operation steps of the "boiling dispersion" mixing treatment in step (2) are as follows: the CNTs mixed solution and the Cu-Ni-Si alloy powder are poured into a round-bottom flask with a vent valve, and then the flask is installed on a rotary evaporator. The vacuum pump is turned on to evacuate the flask, and the vent valve is immediately closed after the evacuation. The rotary switch is then turned on to a speed of 60 r / min~70 r / min, and the heating switch is turned on to make the water bath temperature reach 60℃~80℃, and the insulation time is 1h~3h.

4. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (2), the drying temperature is 70°C to 80°C, and the drying time is 10h to 14h.

5. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (3), the spark plasma sintering temperature is 700°C~900°C, the heating rate is 50~200°C / min, and the holding time is 5 min~20 min.

6. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (3), the temperature of the solution treatment is 800°C to 1000°C, the time of the solution treatment is 0.5 h to 2 h, and the cooling is carried out by water quenching.

7. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (4), the temperature of the cold rolling treatment is 150°C to 300°C, the number of rolling passes is 3 to 6 times, and the rolling amount of each pass is 1 mm to 2 mm.

8. The method for preparing a high-performance copper-based lead frame material using powder metallurgy technology according to claim 1, characterized in that: In step (4), the aging treatment temperature is 350°C to 550°C, the aging treatment time is 2 h to 8 h, and cooling is performed by water quenching.

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