Special-shaped copper strip for lead frame with multi-scale precipitated phases and preparation process of special-shaped copper strip

Abstract

The invention relates to the technical field of lead frame production, in particular to a special-shaped copper strip for a lead frame with multi-scale precipitated phases and a preparation process thereof.The copper strip comprises a copper-based alloy body with a special-shaped section, and nanoscale precipitated phases, submicron precipitated phases and micron precipitated phases which are distributed in a gradient mode exist on the copper-based alloy body at the same time. The nanoscale precipitated phases are distributed in an intragranular box dislocation region, the submicron precipitated phases and the micron precipitated phases are distributed in a grain boundary, and the nanoscale precipitated phases, the submicron precipitated phases and the micron precipitated phases are in a mixed state. The preparation process comprises the following steps: S1, preparing raw materials; s2, alloy smelting and copper strip cast ingot preparation molding; s3, copper strip forming; s4, continuously and precisely stamping to form a special-shaped section; s5, multi-scale precipitated phase regulation and control heat treatment; s6, finishing and post-treatment are conducted; and S7, manufacturing the lead frame. The copper strip manufactured through the manufacturing technology of the technical scheme has multi-scale precipitated phases, and the strength and the conductivity of the copper strip are cooperatively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lead frame production, in particular to a special-shaped copper strip for lead frame with multi-scale precipitated phases and a preparation process thereof. BACKGROUND

[0002] The existing copper strip for lead frame is mainly Cu-Fe-P and Cu-Ni-Si rectangular copper strip, which forms nano-scale precipitated phases (such as Fe2P and Ni2Si) through single-stage aging to achieve a strength of 350-600 MPa and a conductivity of ≥80% IACS. However, the precipitated phase is single in scale, mainly in nano-scale, and the balance between high strength and high conductivity is bottlenecked, and the cross section of the copper strip is a standard rectangle, which cannot directly adapt to the special-shaped assembly requirements of complex packaging. SUMMARY

[0003] In view of the above technical deficiencies, the purpose of the present application is to provide a special-shaped copper strip for lead frame with multi-scale precipitated phases and a preparation process thereof, wherein the special-shaped copper strip for lead frame with multi-scale precipitated phases comprises a copper-based alloy body with a special-shaped cross section, and the copper-based alloy body simultaneously has gradiently distributed nano-scale, sub-micron-scale and micron-scale three-stage precipitated phases, the nano-scale is distributed in the intracrystalline box dislocation zone, the sub-micron-scale and micron-scale precipitated phases are distributed in the grain boundary, and the nano-scale, sub-micron-scale and micron-scale precipitated phases are in a mixed form.

[0004] In order to prepare the special-shaped copper strip with multi-scale precipitated phases, the following features are specifically provided: A preparation process of a special-shaped copper strip for lead frame with multi-scale precipitated phases is applied to the special-shaped copper strip for lead frame with multi-scale precipitated phases, and comprises the following steps: S1, raw material preparation; S2, alloy smelting and copper strip ingot preparation forming; S3, copper strip forming; S4, continuous precision stamping to form a special-shaped cross section; S5, multi-scale precipitated phase regulation heat treatment; S6, finishing and post-processing; S7, making a lead frame.

[0005] In order to obtain a high-strength copper strip as a basis, the following features are specifically provided: the S2 specifically comprises the following steps: S2a, smelting alloy element raw materials by adopting medium-frequency induction, controlling the smelting temperature to be 1100-1200℃, and introducing argon; S2b, making a cast ingot with a target diameter and thickness by adopting horizontal continuous casting, the cross section of the cast ingot is circular, the diameter and thickness of the cast ingot are designed according to the size of the copper strip, and the cooling speed is controlled to be 5-10℃ / s; S2c, the ingot is subjected to homogenization annealing.

[0006] In order to form the special-shaped copper strip, the following features are specifically provided: the S4 specifically comprises the following steps: S4a, the copper strip is stepwise conveyed in a horizontal direction by a copper strip conveying device, so that the copper strip sequentially passes through multiple stamping die sets for multi-point stamping; S4b, the rolling temperature is 200-300 DEG C, the pass reduction is controlled to be 5%-15%, the pass reduction of the later passes is gradually reduced to avoid cross-section edge cracking, and the final pass ensures the size tolerance of ±0.2 mm.

[0007] In order to make the copper strip have multiple precipitation phases, the following features are specifically provided: the S5 specifically comprises the following steps: S5a, the solid solution treatment is set to a temperature of 900-950 DEG C, and the alloying elements Fe, P, Ni and Si are fully dissolved into the copper matrix by heat preservation for 1-2 h, and then water quenching is adopted for rapid cooling at a cooling speed of ≥100 DEG C / s; S5b, cold rolling deformation is performed at a deformation amount of 30%-50% and a cold rolling speed of 10-15 m / min, the rolling force is uniformly controlled, dislocations and grain boundaries are introduced as nucleation sites of the precipitation phase, and the multiple-scale precipitation phase is promoted to be dispersedly distributed; S5c, the hierarchical aging treatment is performed at a first aging temperature of 400-450 DEG C for 2-3 h to precipitate 10-50 nm nanophase, and at a second aging temperature of 500-550 DEG C for 1-2 h to precipitate 0.1-5 μm submicron phase and micron phase.

[0008] In order to trim the copper strip with multiple-scale precipitation phases to facilitate subsequent assembly of the lead frame, the following features are specifically provided: the S6 specifically comprises the following steps: S6a, straightening treatment is performed by adopting a roller straightening machine for multiple passes of slight reduction, the reduction amount is ≤0.05 mm, the straightness of the special-shaped copper strip is corrected to be ≤0.5 mm / m, and residual stress is eliminated; S6b, surface treatment is performed, the copper strip is subjected to pickling in a 5%-10% sulfuric acid solution to remove the oxide scale, and then is subjected to electrolytic polishing to improve the surface finish to Ra≤0.1 μm, so as to meet the welding requirements of the lead frame; S6c, precise cutting according to a target length, detection of cross-sectional size, tensile strength, electrical conductivity and precipitation phase morphology.

[0009] In order to avoid the demolding difficulty existing in the continuous fine stamping process of the copper strip step-by-step movement of multiple points and the problem of abrasion caused by the movement of the copper strip, the following features are specifically provided: the stamping die set comprises a lower die and an upper die arranged on the movement path of the copper strip, the lower die is provided with a stamping station, the lower die is provided with a limiting wheel for limiting the copper strip at both ends, the lower die is provided with a sinking groove at both sides of the stamping station, the sinking groove is provided with a lifting wheel, and the lifting wheel is completely located in the sinking groove when the lower die and the upper die are closed and is lifted synchronously to lift the copper strip when the upper die moves upward.

[0010] In order to realize the lifting of the lifting wheel following the upward movement of the upper die, the following features are specifically provided: the lifting wheel is rotatably installed on the mounting frame, the mounting frame is provided with a vertical guide rod at the bottom, the guide rod is inserted into the corresponding guide hole arranged in the sinking groove, the top of the guide rod is provided with a bottom plate, a spring is sleeved on the guide rod, the spring is elastically connected between the bottom of the lower die and the bottom plate, and the elastic force of the bottom plate makes the lifting wheel located in the sinking groove. Preferably, the bottom plates on both sides of the stamping station are fixedly connected through horizontal connecting plates, one side of the upper die is provided with a vertical extension plate, and the extension plate is provided with a contact plate extending horizontally below the connecting plate.

[0011] In order to stably move and guide the deformed special-shaped copper strip after being stamped by different stamping die sets, the following features are specifically provided: the limiting wheel is vertically rotatably installed on the adjusting seat, and the adjusting seat is slidingly installed at the horizontal slide rail arranged at both ends of the lower die.

[0012] Preferably, the limiting wheels at the input end of the copper strip have two, and the limiting wheel at the output end of the copper strip has one and is attached to the non-processing side of the copper strip.

[0013] The beneficial effects of the present application compared with the prior art are: Firstly, the precipitated phase size of the copper strip in the present application covers a composite system of nano level, sub-micron level and micron level. The nano-level precipitated phase hinders the movement of dislocations to improve the strength, the micron-level precipitated phase optimizes the stress distribution, and the sub-micron-level connects the two to realize the synergistic improvement of the strength and conductivity of the copper strip.

[0014] Secondly, the preparation process in the present application fully dissolves alloying elements into the copper matrix through solid solution treatment to provide a composition basis for subsequent precipitated phase generation. Intermediate cold rolling deformation introduces dislocations and grain boundaries as nucleation sites for precipitated phases, promoting the dispersion distribution of multi-scale precipitated phases. The staged aging treatment realizes the stage-by-stage precipitation of different scale phases.

[0015] Thirdly, in the preparation process, the upper die of the stamping die set drives the lifting wheels in the sinking grooves on both sides of the stamping station to move up after the stamping is completed, the lifting wheels lift the copper strip, which facilitates the copper strip to move away from the stamping station and facilitates subsequent movement, and the sliding friction force between the copper strip and the lower die is changed into rolling friction force when the copper strip moves, so that the abrasion of the surface of the copper strip is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0017] Figure 1 It is a side view of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 1 .

[0018] Figure 2 It is a sectional view of A-A of Figure 1 .

[0019] Figure 3 It is a perspective view of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 1 .

[0020] Figure 4 It is a side view of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 2 .

[0021] Figure 5 It is a sectional view of B-B of Figure 4 .

[0022] Figure 6 It is a perspective view of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 2 .

[0023] Figure 7 It is a perspective structural decomposition of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 1 .

[0024] Figure 8 It is a perspective structural decomposition of the stamping die set in the preparation process of the special-shaped copper strip for lead frame with multi-scale precipitated phase Figure 2 .

[0025] Explanation of reference signs: 1, lower die; 1a, stamping station; 1b, limiting wheel; 1b1, adjusting seat; 1c, sinking groove; 1c1, guide hole; 1d, lifting wheel; 1d1, mounting frame; 1d2, guide rod; 1d3, bottom plate; 1d4, spring; 1d5, connecting plate; 1e, sliding rail; 2, upper die; 2a, extension plate; 2a1, contact plate. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0027] A special-shaped copper strip for lead frames with multi-scale precipitates, comprising a copper-based alloy body with a special-shaped cross section, wherein there are three levels of nano-scale, sub-micron-scale and micron-scale precipitates in gradient distribution on the copper-based alloy body, the nano-scale precipitates are distributed in the intracrystalline box dislocation zone, and the sub-micron-scale and micron-scale precipitates are distributed at the grain boundaries, and the nano-scale, sub-micron-scale and micron-scale precipitates are in a mixed form.

[0028] The precipitates of the special-shaped copper strip for lead frames with multi-scale precipitates in the present application cover a composite system of nano-scale, sub-micron-scale and micron-scale. The nano-scale precipitates hinder dislocation movement to improve strength, the micron-scale precipitates optimize stress distribution, and the sub-micron-scale bridges the two to realize the synergistic improvement of the strength and conductivity of the copper strip. The cross section of the copper-based alloy body is non-traditional rectangular, containing specific grooves, bosses or stepped structures, for adapting to the packaging assembly requirements of subsequent lead frames.

[0029] In order to prepare the special-shaped copper strip with multi-scale precipitates, the following features are specifically provided: a preparation process of a special-shaped copper strip for lead frames with multi-scale precipitates, applied to a special-shaped copper strip for lead frames with multi-scale precipitates, comprising the following steps: S1, raw material preparation; S2, alloy smelting and copper strip ingot preparation and forming; S3, copper strip forming; S4, forming a special-shaped cross section by continuous precision stamping; S5, multi-scale precipitate regulation and heat treatment; S6, finishing and post-processing; S7, making a lead frame.

[0030] In order to obtain a high-strength copper strip as a basis, the following features are specifically provided: S2 specifically comprises the following steps: S2a, adopt intermediate frequency induction melting alloy element raw material, control the melting temperature 1100~1200℃, pass in argon gas; S2b, adopt horizontal continuous casting ingot to make the ingot that meets the target diameter and thickness, the cross section of the ingot is circular, the diameter and thickness of the ingot are designed according to the size of the copper strip, and the cooling speed is controlled at 5~10℃ / s; S2c, the ingot is annealed by homogenization.

[0031] In this embodiment, the raw material of intermediate frequency induction melting can be selected from high-purity electrolytic copper (Cu≥99.99%) and Fe, P, Ni, Si, Ti and other alloy element raw materials. Argon gas is passed in during the melting process to prevent oxidation. The cooling speed of the ingot is controlled at 5~10℃ / s to reduce composition segregation, and the final annealing eliminates casting stress and composition segregation, laying a foundation for uniform nucleation of subsequent multi-scale precipitated phases.

[0032] In order to form a special-shaped copper strip, the following features are specifically provided: S4 specifically includes the following steps: S4a, the copper strip is stepwise conveyed in the horizontal direction by a copper strip conveying device, so that the copper strip passes through multiple stamping die sets for multi-point stamping in sequence; S4b, the rolling temperature is 200~300℃, the pass reduction is controlled at 5%~15%, the pass reduction of the later passes is gradually reduced to avoid cross section edge cracking, and the final pass ensures the size tolerance ±0.2mm.

[0033] In order to make the copper strip have multiple precipitated phases, the following features are specifically provided: S5 specifically includes the following steps: S5a, the solid solution treatment is set at a temperature of 900~950℃, and the alloy elements Fe, P, Ni and Si are fully dissolved into the copper matrix for 1~2h, and water quenching is used for rapid cooling with a cooling speed ≥100℃ / s; S5b, cold rolling deformation, deformation amount 30%~50%, cold rolling speed 10~15m / min, control rolling force uniformly, introduce dislocation and grain boundary as nucleation sites of precipitated phase, promote multi-scale precipitated phase to be dispersedly distributed; S5c, hierarchical aging treatment, first aging 400~450℃ / 2~3h, precipitating 10~50nm nanophase, second aging 500~550℃ / 1~2h, precipitating 0.1~5μm submicron phase and micron phase.

[0034] In this embodiment, the solid solution treatment fully dissolves the alloy elements into the copper matrix to provide a composition basis for subsequent precipitated phase generation. Intermediate cold rolling deformation introduces dislocations and grain boundaries as nucleation sites of precipitated phase, promoting multi-scale precipitated phase to be dispersedly distributed. Hierarchical aging treatment realizes the precipitation of different scale phases in stages.

[0035] In order to trim the copper strip with multi-scale precipitated phase for subsequent assembly of lead frame, the following features are specifically provided: S6 specifically includes the following steps: S6a, straightening treatment, adopting roll straightening machine multi-pass slight reduction, reduction ≤0.05mm, correcting the straightness of the profiled copper strip ≤0.5mm / m, eliminating residual stress; S6b, surface treatment, pickling with 5%-10% sulfuric acid solution, removing oxide skin, and then electrolytic polishing to improve surface finish to Ra≤0.1μm, meeting the welding requirements of lead frame; S6c, precise cutting according to target length, detecting cross-sectional size, tensile strength, electrical conductivity and precipitated phase morphology.

[0036] Reference Figures 1 to 8 In order to avoid the demolding difficulty and the abrasion problem of copper strip movement during the continuous fine stamping process of multiple points, the following features are specifically provided: the stamping die set includes a lower die 1 and an upper die 2 arranged on the copper strip movement path, the lower die 1 is provided with a stamping station 1a, the lower die 1 is provided with a limiting wheel 1b at both ends for limiting the copper strip, the lower die 1 is provided with a sinking groove 1c at both sides of the stamping station 1a, the sinking groove 1c is provided with a lifting wheel 1d, the lifting wheel 1d is completely located in the sinking groove 1c when the lower die 1 and the upper die 2 are closed, and the lifting wheel 1d is lifted synchronously when the upper die 2 is moved upward to lift the copper strip.

[0037] In this embodiment, the copper strip conveying device steps in the horizontal direction to convey the copper strip, so that the copper strip passes through a plurality of stamping die sets in turn, the lower die 1 of each stamping die set is fixed, and the upper die 2 is driven by the hydraulic cylinder to move up and down in the vertical direction, so as to realize the stamping processing of the copper strip at this position. The stamping die set in this embodiment limits the moving copper strip through the limiting wheels 1b on both sides, ensures that the stamping position of the copper strip falls accurately into the stamping station 1a, and lifts the lifting wheel 1d in the sinking groove 1c on both sides of the stamping station 1a through the upper die 2 when the stamping is completed. The lifting wheel 1d lifts the copper strip to facilitate the copper strip to separate from the stamping station 1a for subsequent movement, and changes the sliding friction between the copper strip and the lower die 1 into rolling friction when the copper strip moves, thereby reducing the abrasion of the surface of the copper strip.

[0038] In order to realize the lifting of the lifting wheel 1d following the upward movement of the upper die 2, the following features are specifically provided: the lifting wheel 1d is rotatably installed on the mounting bracket 1d1, the mounting bracket 1d1 is provided with a vertical guide rod 1d2 at the bottom, the guide rod 1d2 is inserted into the corresponding guide hole 1c1 provided in the sinking groove 1c, the guide rod 1d2 is provided with a bottom plate 1d3 at the top, a spring 1d4 is sleeved on the guide rod 1d2, the spring 1d4 elastically connects the bottom of the lower die 1 and the bottom plate 1d3, and the elastic force of the bottom plate 1d3 makes the lifting wheel 1d located in the sinking groove 1c; The bottom plate 1d3 on both sides of the punching station 1a is fixedly connected through the horizontal connecting plate 1d5, and the upper die 2 is provided with a vertical extension plate 2a, and the bottom of the extension plate 2a is provided with a contact plate 2a1 extending horizontally below the connecting plate 1d5.

[0039] As shown in Figures 2 to 5 , the lifting wheel 1d in the embodiment is installed on the mounting bracket 1d1, the guide rod 1d2 at the bottom of the mounting bracket 1d1 extends below the lower die 1 through the guide hole 1c1 of the sunken groove 1c, the guide hole 1c1 guides the movement of the lifting wheel 1d, and the bottom plate 1d3 at the bottom end of the guide rod 1d2 is subjected to the elastic force of the spring 1d4 to cooperate with the gravity of the lifting wheel 1d to ensure that the lifting wheel 1d is completely located inside the sunken groove 1c in a non-external force contact state, and does not affect the punching of the copper strip by the upper die 2. When the punching is completed, the upper die 2 moves upward to drive the extension plate 2a and the contact plate 2a1 to move upward, and the contact plate 2a1 moves upward to abut below the connecting plate 1d5, thereby driving the lifting wheels 1d on both sides of the punching station 1a to move upward synchronously. In this process, the bottom plate 1d3 compresses the spring 1d4, and the lifting wheel 1d lifts the copper strip at the punching station 1a to make it separate from the punching station 1a, thereby facilitating subsequent movement.

[0040] In order to stably move and guide the deformed copper strip after punching by different punching die sets, the following features are specifically provided: The vertically rotating limiting wheel 1b is installed on the adjusting seat 1b1, and the adjusting seat 1b1 is slidingly installed on the horizontal slide rail 1e provided at both ends of the lower die 1.

[0041] The limiting wheel 1b at the input end of the lower die 1 has two, and the limiting wheel 1b at the output end of the lower die 1 has one and abuts against the non-processing side of the copper strip.

[0042] As shown in Figure 7 and Figure 8 , in the embodiment, the limiting wheel 1b is vertically rotatably installed on the adjusting seat 1b1, so that it abuts against the two sides of the copper strip to limit the movement of the copper strip, and converts the sliding friction into rolling friction when the copper strip moves, thereby protecting the side edges of the copper strip. In the embodiment, the limiting wheel 1b at the input end of the lower die 1 has two, and the adjusting seats 1b1 of the two limiting wheels 1b are slidingly adjusted in position along the slide rail 1e, so that the limiting wheels 1b abut against the two sides of the copper strip to limit the movement of the copper strip. The limiting wheel 1b at the output end of the lower die 1 has one and abuts against the non-processing side of the copper strip, thereby releasing the side of the copper strip subjected to punching, avoiding affecting the punched part by the limiting wheel 1b, and the positions of the two limiting wheels 1b at the output end of the subsequent punching die set can be set according to the size of the copper strip after punching by the previous punching die set.

[0043] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A shaped copper strip for lead frames with multi-scale precipitated phases, characterized in that, The invention includes a copper-based alloy body with an irregular cross-section, on which three levels of precipitates—nanoscale, submicron-scale, and micron-scale—are simultaneously distributed in a gradient. The nanoscale precipitates are distributed in the dislocation regions within the grains, while the submicron-scale and micron-scale precipitates are distributed at the grain boundaries. The nanoscale, submicron-scale, and micron-scale precipitates are in a mixed morphology.

2. A process for fabricating a shaped copper strip for a leadframe with multi-scale precipitated phases, applied to the shaped copper strip for a leadframe with multi-scale precipitated phases as described in claim 1, characterized in that, Includes the following steps: S1. Raw material preparation; S2, alloy smelting and copper strip ingot preparation and molding; S3, Copper strip forming; S4. Continuous precision stamping forms irregular cross-sections; S5. Multi-scale precipitate phase control heat treatment; S6. Finishing and post-processing; S7. Make the lead frame.

3. The process for fabricating a shaped copper strip with multi-scale precipitates for a leadframe according to claim 2, characterized in that, S2 specifically includes the following steps: S2a. Use medium-frequency induction melting to melt alloy element raw materials, control the melting temperature to 1100~1200℃, and introduce argon gas. S2b: Ingots with the target diameter and thickness are made by horizontal continuous casting. The ingot cross-section is circular. The ingot diameter and thickness are designed according to the copper strip size. The cooling rate is controlled at 5~10℃ / s. S2c, the ingot is homogenized and annealed.

4. The process for fabricating a shaped copper strip with multi-scale precipitated phases for a leadframe according to claim 2, characterized in that, S4 specifically includes the following steps: S4a. The copper strip is conveyed horizontally in a stepping manner by the copper strip conveyor, so that the copper strip passes through multiple stamping dies in sequence for multi-point stamping. S4b, rolling temperature 200~300℃, the reduction per pass is controlled at 5%~15%, the reduction of subsequent passes is gradually reduced to avoid cracking at the edge of the cross section, and the final pass ensures dimensional tolerance ±0. Upper die (2) mm.

5. The process for fabricating a shaped copper strip with multi-scale precipitates for a leadframe according to claim 2, characterized in that, S5 specifically includes the following steps: S5a, the solution treatment temperature is set at 900~950℃, and the holding time is 1~2h to fully dissolve the alloying elements Fe, P, Ni and Si into the copper matrix. Water quenching is used for rapid cooling, and the cooling rate is ≥100℃ / s. S5b, cold rolling deformation, deformation amount 30%~50%, cold rolling speed 10~15m / min, control rolling force uniformity, introduce dislocations and grain boundaries as nucleation sites for precipitates, and promote multi-scale precipitate dispersion; S5c, graded aging treatment: first aging at 400~450℃ / 2~3h, precipitating 10~50nm nanophase; second aging at 500~550℃ / 1~2h, precipitating 0.1~5μm submicron and micron phases.

6. The process for fabricating a shaped copper strip with multi-scale precipitates for a leadframe according to claim 2, characterized in that, S6 specifically includes the following steps: S6a. Straightening treatment: Use a roller straightener to apply multiple light pressures, with a pressure amount ≤0.05mm, to correct the straightness of the irregular copper strip to ≤0.5mm / m and eliminate residual stress. S6b, Surface treatment: pickling with 5%~10% sulfuric acid solution to remove oxide scale, followed by electrolytic polishing to improve surface finish to Ra≤0.1μm, meeting the soldering requirements of the lead frame; S6c: Precision cutting according to the target length, and detection of cross-sectional dimensions, tensile strength, conductivity and morphology of precipitated phases.

7. The process for fabricating a shaped copper strip with multi-scale precipitated phases for a leadframe according to claim 4, characterized in that, The stamping die assembly includes a lower die (1) and an upper die (2) disposed on the copper strip moving path. The lower die (1) is provided with a stamping station (1a). The lower die (1) is provided with limiting wheels (1b) at both ends to limit the copper strip. The lower die (1) is provided with sinking grooves (1c) on both sides of the stamping station (1a). Lifting wheels (1d) are provided in the sinking grooves (1c). When the lower die (1) and the upper die (2) are closed, the lifting wheels (1d) are completely located in the sinking grooves (1c) and move upward synchronously to lift the copper strip when the upper die (2) moves upward.

8. The process for fabricating a shaped copper strip with multi-scale precipitated phases for a leadframe according to claim 7, characterized in that, The lifting wheel (1d) is rotatably mounted on the mounting frame (1d1). The bottom of the mounting frame (1d1) is provided with a vertical guide rod (1d2). The guide rod (1d2) is inserted into the corresponding guide hole (1c1) provided in the sinking groove (1c). The top of the guide rod (1d2) is mounted with a base plate (1d3). A spring (1d4) is sleeved on the guide rod (1d2). The spring (1d4) elastically connects the bottom of the lower mold (1) and the base plate (1d3). The elastic force applied by the base plate (1d3) keeps the lifting wheel (1d) in the sinking groove (1c). The bottom plates (1d3) on both sides of the stamping station (1a) are fixedly connected by a horizontal connecting plate (1d5). A vertical extension plate (2a) is installed on one side of the upper die (2). A contact plate (2a1) extending horizontally to the bottom of the extension plate (2a) is provided.

9. The process for fabricating a shaped copper strip with multi-scale precipitated phases for a leadframe according to claim 7, characterized in that, The vertical rotation of the limiting wheel (1b) is mounted on the adjusting seat (1b1), and the adjusting seat (1b1) is slidably mounted on the horizontal slide rails (1e) set at both ends of the lower mold (1).

10. The process for fabricating a shaped copper strip with multi-scale precipitates for a leadframe according to claim 9, characterized in that, The lower die (1) has two limiting wheels (1b) at the copper strip input end, and one limiting wheel (1b) at the copper strip output end of the lower die (1) is attached to the non-processed side of the copper strip.

Images