Bonding copper wire and preparation method and application thereof

Abstract

The application relates to the technical field of bonding wire for semiconductor packaging, and discloses a bonding copper wire and a preparation method and application thereof. The chemical composition of the bonding copper wire includes, in terms of weight percentage: 42-48 ppm of phosphorus, 32-38 ppm of silver, 8-12 ppm of lanthanum, 8-12 ppm of yttrium, and the balance of copper; the breaking force of the bonding copper wire is greater than or equal to 7.5 cN, the elongation rate is 11.0%-15%, and the reliability is greater than or equal to 300 cycles. The application adds 8-12 ppm of lanthanum elements, 8-12 ppm of yttrium elements, 32-38 ppm of silver elements and 42-48 ppm of phosphorus elements in the bonding copper wire, and the multiple micro-alloying has a synergistic effect, can play a better corrosion-resistant welding effect than single elements, and improves the comprehensive performance of the alloy.

Description

Technical Field

[0001] This invention relates to the field of bonding wire technology for semiconductor packaging, specifically to a bonding copper wire and its preparation method and application. Background Technology

[0002] Bonding wires, as one of the essential materials in electronic packaging, function to achieve electrical connections between semiconductor chips and pins, playing a crucial role in the introduction and extraction of current and signals between the chip and the external environment. Currently, 80% of packaging on the market uses wire bonding, and the performance of the bonding wire directly affects the performance of the IC chip. With the trend of miniaturization, modularization, and high integration in electronic products, bonding wires are required to have superior mechanical and processing properties. Compared with gold and aluminum wires, copper has a significant cost advantage and also possesses excellent electrical and thermal conductivity, as well as low hardness and good chemical stability, making it a strong competitor in the packaging market.

[0003] The conventional method for preparing copper-based wire involves first preparing a rod blank, followed by multiple passes of rough drawing, intermediate drawing, and micro drawing. After plastic deformation, the internal grains interact and rotate relative to the external force axis. Most grains aggregate to certain orientations, forming a deformed texture. During the stretching process, the rotation of the crystals causes the slip direction to be parallel to a single stretching axis, limiting the surface tension of the mechanical properties. This results in poor mechanical properties, low reliability, low production efficiency, and cumbersome and costly processing steps for bonded copper wire. Currently, the main alloying elements for copper wire are Ag, Pd, and Ca. The addition of these elements can effectively improve the oxidation resistance and ductility of pure copper, but the defects of poor mechanical properties and low reliability still exist.

[0004] Therefore, how to obtain bonding copper wires with good mechanical properties and high reliability is one of the technical problems that urgently need to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention provides bonding copper wire with good mechanical properties and high reliability.

[0006] The present invention also provides a method for preparing the above-mentioned bonding copper wire.

[0007] In a first aspect, the present invention provides a bonding copper wire, wherein the chemical composition of the bonding copper wire, by weight percentage, comprises: phosphorus 42ppm-48ppm, silver 32ppm-38ppm, lanthanum 8ppm-12ppm, yttrium 8ppm-12ppm, and the balance copper.

[0008] The bonding copper wire has a breaking strength ≥7.5cN, an elongation of 11.0%-15.0%, and a reliability ≥300 cycles.

[0009] In one optional embodiment, the chemical composition of the bonding copper wire includes: phosphorus 44ppm-46ppm, silver 34ppm-36ppm, lanthanum 9ppm-11ppm, yttrium 9ppm-11ppm, and balance copper.

[0010] The bonding copper wire has a breaking strength ≥7.6cN and an elongation of 11.5%-12%.

[0011] In one optional embodiment, the chemical composition of the bonding copper wire includes: 45 ppm phosphorus, 35 ppm silver, 10 ppm lanthanum, 10 ppm yttrium, and the balance copper.

[0012] The bonding copper wire has a breaking strength of 7.9 cN and an elongation of 11.6%.

[0013] Secondly, the present invention also provides a method for preparing the above-mentioned bonding copper wire, comprising the following steps:

[0014] (1) Phosphorus, silver, lanthanum and yttrium are mixed with a portion of high-purity copper and then smelted once to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy;

[0015] (2) The phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper are mixed and then smelted twice to obtain a copper rod with a diameter of 8mm-10mm;

[0016] (3) The copper rod is annealed once and then continuously rolled to a diameter of 4.2mm-4.4mm;

[0017] (4) The rolled copper rod is subjected to secondary annealing and then rotary forging to obtain copper wire with a diameter of 2.0mm-2.1mm;

[0018] (5) The copper wire after rotary forging is subjected to continuous drawing and undrawing wire drawing and zero-difference sliding wire drawing to obtain copper wire with a diameter of 0.018mm-0.030mm;

[0019] (6) The copper wire is subjected to three annealing processes to obtain the bonding copper wire.

[0020] In one alternative implementation, the elongation rate during the continuous calendering step is 18%-20%.

[0021] In one optional embodiment, the number of rotary forgings includes at least two times; in the first rotary forging, the diameter is forged to 2.9mm-3.1mm; in the second rotary forging, the diameter is forged to 2.0mm-2.1mm.

[0022] In one optional embodiment, the primary annealing temperature is 500℃-600℃, and the primary annealing time is 4h-5h; the annealing is performed under vacuum conditions.

[0023] In one optional embodiment, the secondary annealing temperature is 400℃-500℃, the secondary annealing time is 2h-3h, and the annealing atmosphere is an inert atmosphere.

[0024] In one optional embodiment, the three annealing temperatures are 380℃-450℃, the three annealing times are 0.3s-0.4s, and the annealing atmosphere is a nitrogen and hydrogen atmosphere.

[0025] In one alternative embodiment, the phosphorus content in the phosphorus-copper master alloy is 1.0wt%-1.5wt%.

[0026] In one alternative embodiment, the silver content in the silver-copper master alloy is 0.8wt%-1.1wt%.

[0027] In one optional embodiment, the lanthanum-yttrium-copper master alloy contains 0.75wt%-1.5wt% lanthanum and 0.6wt%-0.8wt% yttrium.

[0028] In one optional embodiment, the temperature of the first melting is 1000℃-1600℃, and the time is 4h-6h.

[0029] In one optional embodiment, the secondary melting temperature is 1200℃-1250℃ and the time is 8h-10h.

[0030] In one alternative implementation, the pull-and-retract step includes at least two steps.

[0031] In one optional embodiment, during the first continuous drawing and undrawing process, the wire is drawn and undrawn to a diameter of 0.3 mm-0.4 mm, an elongation of 15%-18%, a speed of 300 m / min-400 m / min, a drawing solution concentration of 1.5 wt%-2.0 wt%, and an annealing temperature of 350℃-400℃.

[0032] In one optional embodiment, during the second continuous drawing and unwinding process, the wire is drawn and unwinded to a diameter of 0.08 mm to 0.12 mm, an elongation of 13% to 16%, a speed of 300 m / min to 500 m / min, a drawing solution concentration of 1.0 wt% to 1.5 wt%, and an annealing temperature of 340°C to 390°C.

[0033] In one alternative implementation, the zero-difference wire drawing step includes at least three steps.

[0034] In one optional embodiment, during the first zero-difference drawing, the wire is drawn to a diameter of 0.05mm-0.06mm, an elongation of 10%-13%, a speed of 550m / min-650m / min, and a drawing solution concentration of 2.0wt%-2.5wt%.

[0035] In one optional embodiment, during the second zero-difference drawing process, the wire is drawn to a diameter of 0.03 mm to 0.04 mm, with an elongation of 8% to 10%, at a speed of 750 m / min to 850 m / min, and the concentration of the drawing solution is 1.5 wt% to 2.0 wt%.

[0036] In one optional embodiment, during the third zero-difference drawing process, the wire is drawn to a diameter of 0.01 mm to 0.02 mm, with an elongation of 8% to 9%, a speed of 950 m / min to 1050 m / min, and a drawing solution concentration of 1.0 wt% to 1.5 wt%.

[0037] In one alternative implementation, after secondary melting, a directional solidification and continuous casting step is further included.

[0038] In one optional embodiment, the copper rod is further subjected to a surface treatment step in sequence.

[0039] In one optional embodiment, the surface treatment agent comprises: 3wt%-7wt% sulfuric acid, 3wt%-7wt% nitric acid, 0.03wt%-0.07wt% OP-10 agent, and the remainder being purified water.

[0040] In one optional embodiment, the copper wire after rotary forging is further subjected to a stripping process and a non-destructive testing step, and the diameter of the copper wire after stripping is 1.8mm-2.2mm.

[0041] In one optional embodiment, the peeling speed is 15m / min-20m / min, and the back tension is 150N-180N.

[0042] In one optional embodiment, the process further includes a degreasing and polishing step on the drawn copper wire.

[0043] In one optional embodiment, the degreasing and polishing treatment temperature is 40℃-50℃.

[0044] In one alternative embodiment, the polishing agent comprises: 10wt%-15wt% sodium hydroxide, 18wt%-23wt% sodium phosphate, 10wt%-15wt% sodium carbonate, 1wt%-3wt% OP-10 agent, and the remainder being water.

[0045] In one alternative implementation, in step (2), the drawing speed in continuous casting is 50 m / min-60 m / min.

[0046] Thirdly, the present invention also provides an application of the above-mentioned bonding copper wire in electronic packaging.

[0047] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0048] 1. The bonding copper wire provided by this invention has the following chemical composition: phosphorus 42ppm-48ppm, silver 32ppm-38ppm, lanthanum 8ppm-12ppm, yttrium 8ppm-12ppm, and balance copper; the bonding copper wire has a breaking strength ≥7.5cN, an elongation of 11.0%-15.0%, and a reliability ≥300 cycles. This invention adds 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, 32ppm-38ppm silver, and 42ppm-48ppm phosphorus to the bonding copper wire. The synergistic effect of these multi-element microalloying elements allows for better corrosion resistance and welding performance compared to single-element additions, improving the overall performance of the alloy. Specifically, adding phosphorus to high-purity copper can eliminate oxygen in the copper alloy without affecting electrical and thermal conductivity; adding yttrium can refine copper grains, effectively reducing impurities, weakening lattice distortion, reducing electron scattering probability, and further improving conductivity. High efficiency; the addition of lanthanum can inhibit recrystallization nucleation and growth, and can work in conjunction with phosphorus to promote grain refinement and enhance the mechanical properties of the bonded copper wire; at the same time, lanthanum can also effectively improve sphericity during the bonding process; the addition of silver can react with the copper matrix to form solid solutions or intermetallic compounds. These interface structures and phase transformation processes can improve the mechanical strength and corrosion resistance of the bonded copper wire, reduce the hardness of the copper wire, and enhance its bonding ability with the AL pad; at the same time, the addition of silver can improve the heat dissipation performance of the copper wire, enabling it to dissipate heat more effectively in high-temperature environments, maintain stable performance, and improve its reliability.

[0049] 2. The method for preparing the bonded copper wire provided by the present invention includes the following steps: Phosphorus, silver, lanthanum, and yttrium are mixed with a portion of high-purity copper and then smelted once to obtain a phosphorus-copper master alloy, a silver-copper master alloy, and a lanthanum-yttrium-copper master alloy; the phosphorus-copper master alloy, the silver-copper master alloy, and the lanthanum-yttrium-copper master alloy are mixed with the remaining high-purity copper and then smelted a second time to obtain a copper rod with a diameter of 8mm-10mm; the copper rod is subjected to a first annealing treatment, followed by continuous rolling to a diameter of 4.2mm-4.4mm; the rolled copper rod is subjected to a second annealing treatment, followed by rotary forging to obtain a copper wire with a diameter of 2.0mm-2.1mm; the rotary forged copper wire is subjected to continuous drawing and annealing wire drawing and zero-difference sliding wire drawing to obtain a copper wire with a diameter of 0.018mm-0.030mm; the copper wire is subjected to a third annealing treatment to obtain the bonded copper wire. Because the content of added elements lanthanum, yttrium, silver, and phosphorus is relatively small, the amount added is difficult to control. Directly melting them with copper leads to poor uniformity in the cast rods. This invention first obtains an intermediate alloy through a first melting process, and then melts it a second time with the remaining high-purity copper to better ensure the uniform fusion of the added elements with the base copper elements, thereby ensuring the uniformity of the bonded copper wires. After the first annealing treatment, various structural defects and residual stresses caused by the rolling process of the copper rod can be improved or eliminated, and the workpiece is softened for subsequent processing. It can also refine the grains, improve the microstructure to enhance the mechanical properties of the workpiece, and prepare for the third annealing treatment. After continuous rolling, the thickness of the metal material can be significantly reduced, achieving the effect of reducing its self-weight. The tensile strength is significantly improved, the yield strength is also increased, and the elongation is reduced, which has a significant effect on the strength improvement. After the second annealing, the strength first decreases and then stabilizes, with a consistent overall trend. The microstructure is dense, the grains are fine, and the precipitates are relatively uniform. The rotary forging step refines the grains, eliminates internal micropores, and improves mechanical and electrical properties while reducing internal porosity. The continuous drawing and undrawing process effectively improves batch-to-batch consistency. The slip-free drawing process significantly reduces the occurrence of slippage during drawing, ensuring smooth and consistent operation, preventing stress concentration and uneven deformation caused by slippage, and promoting the homogenization and densification of the internal structure of the bonded copper wire. Under tensile force, stress is more evenly distributed, significantly enhancing its tensile strength. Furthermore, the slip-free drawing process also enhances the uniform deformation capacity of the bonded copper wire during stretching by avoiding localized deformation and damage caused by slippage, allowing the bonded copper wire to withstand greater deformation without easily breaking, thus significantly improving its elongation. In summary, this invention, through the selection of pressure processing techniques, is beneficial to the metallographic microstructure of copper wire, eliminating micropores and improving mechanical properties and reliability.

[0050] The present invention uses a first annealing, a second annealing, and a third annealing to ensure that the elements in the alloy are evenly distributed, thereby improving the mechanical properties of the product.

[0051] 3. The method for preparing bonded copper wire provided by this invention optimizes the production process and parameters of the continuous drawing and annealing process. The wire inlet is 2.0mm-2.1mm, the wire outlet is 0.08mm-0.12mm, the drawing speed is 300m / min-500m / min, and the annealing temperature is 340-400°C. This method replaces the lengthy and complex traditional process, significantly reducing the risk of exposed copper wire being easily oxidized, reducing energy waste, and lowering the environmental impact of production. It meets the requirements of modern industrial production for energy conservation and environmental protection. By limiting the annealing temperature during the continuous drawing and annealing process and annealing the metal immediately after drawing, it is possible to better eliminate or reduce structural defects and residual stress, refine the grain structure, restore plasticity, and thus improve the mechanical properties and reliability of the product.

[0052] 4. The bonding copper wire preparation method provided by this invention, compared with the traditional bonding copper wire drawing process, does not involve the use of molds in rolling and rotary forging, saving production costs and significantly improving production efficiency; then, through continuous drawing and undrawing steps, the stability and consistency of the bonding copper wire are ensured, and the mechanical properties are improved; it can also realize continuous production, reduce waiting and process change time during production, greatly improve production efficiency, and reduce production costs; subsequently, error-free sliding drawing is performed, which greatly reduces the coefficient of friction, avoids the sliding friction that may occur in the traditional drawing process, improves the precision of the bonding copper wire, and ensures the stability of different batches of bonding copper wire.

[0053] 5. The method for preparing bonding copper wire provided by the present invention further includes a peeling step, which can remove surface defects of copper wire to the greatest extent, such as subcutaneous pores, inclusions, mechanical damage, etc. The peeling process makes the surface of the prepared bonding copper wire smooth and uniform, thereby improving the processability and laying the foundation for the stable and consistent tensile strength and elongation of the bonding copper wire.

[0054] 6. The method for preparing bonding copper wire provided by the present invention allows for online non-destructive testing, which can promptly detect residual surface defects such as pores.

[0055] 7. The method for preparing bonded copper wire provided by this invention employs directional solidification and continuous casting technology. The copper rod obtained by directional solidification has fewer internal grain boundaries, impurities, and bubbles, significantly improving the microstructure of the bonded wire and further enhancing its mechanical properties and reliability. The continuous casting technology replaces the cold casting mold in traditional continuous casting with a heated casting mold, thereby avoiding nucleation on the mold wall, completely eliminating equiaxed crystals, and allowing heat to diffuse only in a single direction—the axial direction of the casting billet—to obtain a unidirectional solidified columnar crystal continuous ingot. By controlling the morphology of the solidification interface and the heat flow field distribution of the ingot, the competitive growth of axial grains is promoted, allowing the entire ingot to be gradually controlled by a single grain, achieving single-crystal continuous casting, forming a uniform crystal structure, reducing stress concentration inside the material, and thus improving the tensile strength and fatigue life of the bonded wire. Attached Figure Description

[0056] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0057] Figure 1 This is a process flow diagram of an embodiment of the present invention;

[0058] Figure 2 These are comparative images of the surfaces of the bonding copper wires prepared in Example 1 and Comparative Example 3 of this invention. Detailed Implementation

[0059] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0060] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0061] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0062] In order to solve the problems existing in the above-mentioned related technologies, in a first aspect, the present invention provides a bonding copper wire, wherein the chemical composition of the bonding copper wire, by weight percentage, includes: phosphorus 42ppm-48ppm, silver 32ppm-38ppm, lanthanum 8ppm-12ppm, yttrium 8ppm-12ppm, and the balance copper.

[0063] The bonding copper wire has a breaking strength ≥7.5cN, an elongation of 11.0%-15.0%, and a reliability ≥300 cycles.

[0064] In one optional embodiment, the chemical composition of the bonding copper wire includes: phosphorus 44ppm-46ppm, silver 34ppm-36ppm, lanthanum 9ppm-11ppm, yttrium 9ppm-11ppm, and balance copper.

[0065] The bonding copper wire has a breaking strength ≥7.6cN and an elongation of 11.5%-12%.

[0066] In one optional embodiment, the chemical composition of the bonding copper wire includes: 45 ppm phosphorus, 35 ppm silver, 10 ppm lanthanum, 10 ppm yttrium, and the balance copper.

[0067] The bonding copper wire has a breaking strength of 7.9 cN and an elongation of 11.6%.

[0068] This invention incorporates 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, 32ppm-38ppm silver, and 42ppm-48ppm phosphorus into the bonding copper wire. The synergistic effect of these multi-element microalloying elements provides better corrosion resistance and welding performance compared to single-element additions, thus improving the overall alloy properties. Specifically, adding phosphorus to high-purity copper eliminates oxygen in the copper alloy without affecting electrical and thermal conductivity. Adding yttrium refines the copper grains, effectively reducing impurities, weakening lattice distortion, decreasing electron scattering probability, and further improving conductivity. High efficiency; the addition of lanthanum can inhibit recrystallization nucleation and growth, and can work in conjunction with phosphorus to promote grain refinement and enhance the mechanical properties of the bonded copper wire; at the same time, lanthanum can also effectively improve sphericity during the bonding process; the addition of silver can react with the copper matrix to form solid solutions or intermetallic compounds. These interface structures and phase transformation processes can improve the mechanical strength and corrosion resistance of the bonded copper wire, reduce the hardness of the copper wire, and enhance its bonding ability with the AL pad; at the same time, the addition of silver can improve the heat dissipation performance of the copper wire, enabling it to dissipate heat more effectively in high-temperature environments, maintain stable performance, and improve its reliability.

[0069] Secondly, the present invention also provides a method for preparing the above-mentioned bonding copper wire, comprising the following steps:

[0070] (1) Phosphorus, silver, lanthanum and yttrium are mixed with a portion of high-purity copper and then smelted once to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy;

[0071] (2) The phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper are mixed and then smelted twice to obtain a copper rod with a diameter of 8mm-10mm;

[0072] (3) The copper rod is annealed once and then continuously rolled to a diameter of 4.2mm-4.4mm;

[0073] (4) The rolled copper rod is subjected to secondary annealing and then rotary forging to obtain copper wire with a diameter of 2.0mm-2.1mm;

[0074] (5) The copper wire after rotary forging is subjected to continuous drawing and undrawing wire drawing and zero-difference sliding wire drawing to obtain copper wire with a diameter of 0.018mm-0.030mm;

[0075] (6) The copper wire is subjected to three annealing processes to obtain the bonding copper wire.

[0076] Because the content of added elements lanthanum, yttrium, silver, and phosphorus is relatively small, the amount added is difficult to control. Directly melting them with copper leads to poor uniformity in the cast rods. This invention first obtains an intermediate alloy through a first melting process, and then melts it a second time with the remaining high-purity copper to better ensure the uniform fusion of the added elements with the base copper elements, thereby ensuring the uniformity of the bonded copper wires. After the first annealing treatment, various structural defects and residual stresses caused by the rolling process of the copper rod can be improved or eliminated, and the workpiece is softened for subsequent processing. It can also refine the grains, improve the microstructure to enhance the mechanical properties of the workpiece, and prepare for the third annealing treatment. After continuous rolling, the thickness of the metal material can be significantly reduced, achieving the effect of reducing its self-weight. The tensile strength is significantly improved, the yield strength is also increased, and the elongation is reduced, which has a significant effect on the strength improvement. After the second annealing, the strength first decreases and then stabilizes, with a consistent overall trend. The microstructure is dense, the grains are fine, and the precipitates are relatively uniform. The rotary forging step refines the grains, eliminates internal micropores, and improves mechanical and electrical properties while reducing internal porosity. The continuous drawing and undrawing process effectively improves batch-to-batch consistency. The slip-free drawing process significantly reduces the occurrence of slippage during drawing, ensuring smooth and consistent operation, preventing stress concentration and uneven deformation caused by slippage, and promoting the homogenization and densification of the internal structure of the bonded copper wire. Under tensile force, stress is more evenly distributed, significantly enhancing its tensile strength. Furthermore, the slip-free drawing process also enhances the uniform deformation capacity of the bonded copper wire during stretching by avoiding localized deformation and damage caused by slippage, allowing the bonded copper wire to withstand greater deformation without easily breaking, thus significantly improving its elongation. In summary, this invention, through the selection of pressure processing techniques, is beneficial to the metallographic microstructure of copper wire, eliminating micropores and improving mechanical properties and reliability.

[0077] The present invention uses a first annealing, a second annealing, and a third annealing to ensure that the elements in the alloy are evenly distributed, thereby improving the mechanical properties of the product.

[0078] In one alternative implementation, the elongation rate during the continuous calendering step is 18%-20%.

[0079] In one optional embodiment, the number of rotary forgings includes at least two times; in the first rotary forging, the diameter is forged to 2.9mm-3.1mm; in the second rotary forging, the diameter is forged to 2.0mm-2.1mm.

[0080] Compared with the traditional copper wire drawing process, the rolling and rotary forging processes of this invention do not involve the use of molds, saving production costs and significantly improving production efficiency. Then, through continuous drawing and retraction steps, the stability and consistency of the bonded copper wire are ensured, and the mechanical properties are improved. It can also realize continuous production, reduce waiting and changeover time during the production process, greatly improve production efficiency, and reduce production costs. Subsequently, error-free sliding drawing is performed, which greatly reduces the coefficient of friction and avoids the sliding friction that may occur in the traditional drawing process, improves the precision of the bonded copper wire, and ensures the stability of bonded copper wire in different batches.

[0081] In one optional embodiment, the primary annealing temperature is 500℃-600℃, and the primary annealing time is 4h-5h; the annealing is performed under vacuum conditions.

[0082] In one optional embodiment, the secondary annealing temperature is 400℃-500℃, the secondary annealing time is 2h-3h, and the annealing atmosphere is an inert atmosphere.

[0083] In one optional embodiment, the three annealing temperatures are 380℃-450℃, the three annealing times are 0.3s-0.4s, and the annealing atmosphere is a nitrogen and hydrogen atmosphere.

[0084] In one alternative embodiment, the phosphorus content in the phosphorus-copper master alloy is 1.0wt%-1.5wt%.

[0085] In one alternative embodiment, the silver content in the silver-copper master alloy is 0.8wt%-1.1wt%.

[0086] In one optional embodiment, the lanthanum-yttrium-copper master alloy contains 0.75wt%-1.5wt% lanthanum and 0.6wt%-0.8wt% yttrium.

[0087] In one optional embodiment, the temperature of the first melting is 1000℃-1600℃, and the time is 4h-6h.

[0088] In one optional embodiment, the secondary melting temperature is 1200℃-1250℃ and the time is 8h-10h.

[0089] In one alternative implementation, the pull-and-retract step includes at least two steps.

[0090] In one optional embodiment, during the first continuous drawing and undrawing process, the wire is drawn and undrawn to a diameter of 0.3 mm-0.4 mm, an elongation of 15%-18%, a speed of 300 m / min-400 m / min, a drawing solution concentration of 1.5 wt%-2.0 wt%, and an annealing temperature of 350℃-400℃.

[0091] In one optional embodiment, during the second continuous drawing and unwinding process, the wire is drawn and unwinded to a diameter of 0.08 mm to 0.12 mm, an elongation of 13% to 16%, a speed of 300 m / min to 500 m / min, a drawing solution concentration of 1.0 wt% to 1.5 wt%, and an annealing temperature of 340°C to 390°C.

[0092] This invention optimizes the production process and parameters of the continuous drawing and annealing process, with an infeed wire diameter of 2.0mm-2.1mm, an outfeed wire diameter of 0.08mm-0.12mm, a drawing speed of 300m / min-500m / min, and an annealing temperature of 340-400°C. This replaces the lengthy and complex traditional process, significantly reducing the risk of exposed copper wire being easily oxidized, reducing energy waste, and minimizing the environmental impact of production, thus meeting the requirements of modern industrial production for energy conservation and environmental protection. Furthermore, by limiting the annealing temperature during the continuous drawing and annealing process, and by immediately annealing the metal after drawing, it is possible to better eliminate or reduce structural defects and residual stress, refine the grain structure, and restore plasticity, thereby improving the mechanical properties and reliability of the product.

[0093] In one alternative implementation, the zero-difference wire drawing step includes at least three steps.

[0094] In one optional embodiment, during the first zero-difference drawing, the wire is drawn to a diameter of 0.05mm-0.06mm, an elongation of 10%-13%, a speed of 550m / min-650m / min, and a drawing solution concentration of 2.0wt%-2.5wt%.

[0095] In one optional embodiment, during the second zero-difference drawing process, the wire is drawn to a diameter of 0.03 mm to 0.04 mm, with an elongation of 8% to 10%, at a speed of 750 m / min to 850 m / min, and the concentration of the drawing solution is 1.5 wt% to 2.0 wt%.

[0096] In one optional embodiment, during the third zero-difference drawing process, the wire is drawn to a diameter of 0.01 mm to 0.02 mm, with an elongation of 8% to 9%, a speed of 950 m / min to 1050 m / min, and a drawing solution concentration of 1.0 wt% to 1.5 wt%.

[0097] In one alternative implementation, after secondary melting, a directional solidification and continuous casting step is further included.

[0098] This invention employs directional solidification and continuous casting technology. The copper rods obtained from directional solidification billets have fewer internal grain boundaries, impurities, and bubbles, resulting in excellent processing and performance. The continuous casting technology replaces the cold casting mold in traditional continuous casting with a heated casting mold, thereby avoiding nucleation on the mold wall, completely eliminating equiaxed crystals, and allowing heat to diffuse only in a single direction—the axial direction of the billet. This produces a unidirectional solidified columnar crystal continuous ingot. By controlling the morphology of the solidification interface and the heat flow field distribution of the ingot, the competitive growth of axial grains is promoted, allowing the entire ingot to be gradually controlled by a single grain, thus achieving single-crystal continuous casting.

[0099] In an optional embodiment, the method further includes a surface treatment step on the copper rod.

[0100] In one optional embodiment, the surface treatment agent comprises: 3wt%-7wt% sulfuric acid, 3wt%-7wt% nitric acid, 0.03wt%-0.07wt% OP-10 agent, and the remainder being purified water.

[0101] In one optional embodiment, the copper wire after rotary forging is further subjected to a stripping process and a non-destructive testing step, and the diameter of the copper wire after stripping is 1.8mm-2.2mm.

[0102] The present invention also includes a peeling step, which can remove surface defects of copper wire to the greatest extent, such as subcutaneous pores, inclusions, mechanical damage, etc. The peeling process makes the surface of the prepared bonding copper wire smooth and uniform, thereby improving the processability and laying the foundation for the stable and consistent tensile strength and elongation of the bonding copper wire.

[0103] In one optional embodiment, the peeling speed is 15m / min-20m / min, and the back tension is 150N-180N.

[0104] In one optional embodiment, the process further includes a degreasing and polishing step on the drawn copper wire.

[0105] In one optional embodiment, the degreasing and polishing treatment temperature is 40℃-50℃.

[0106] In one alternative embodiment, the polishing agent comprises: 10wt%-15wt% sodium hydroxide, 18wt%-23wt% sodium phosphate, 10wt%-15wt% sodium carbonate, 1wt%-3wt% OP-10 agent, and the remainder being water.

[0107] In one alternative implementation, in step (2), the drawing speed in continuous casting is 50 m / min-60 m / min.

[0108] Thirdly, the present invention also provides an application of the above-mentioned bonding copper wire in electronic packaging.

[0109] In this invention, the drawing fluid in the continuous drawing and undrawing step has functions such as lubrication, cooling, and cleaning.

[0110] In this invention, the zero-slip wire drawing can achieve independent control of each traction wheel without slippage, and can be arbitrarily matched with molds. Each unit consists of a mold, a drive wheel, and a tension rod. The control system directly controls ten independent drive wheels. The guide wheels in front of and behind the mold can ensure that the wire enters / exits the mold hole directly.

[0111] In this invention, OP-10 was purchased from Tianjin Damao Chemical Reagent Factory and is of AR grade.

[0112] Example 1

[0113] like Figure 1 As shown, this embodiment provides a method for preparing bonding copper wire, including the following steps:

[0114] The composition of the bonded copper wire is as follows: phosphorus 45ppm, silver 35ppm, lanthanum 10ppm, yttrium 10ppm, with the balance being copper.

[0115] (1) Preparation of master alloys: 6N5 copper and phosphorus, 6N5 copper and silver, 6N5 copper, lanthanum and yttrium were smelted at 1180℃, 1250℃ and 1600℃ for 4h, 5h and 6h respectively to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy; wherein, by mass percentage, the phosphorus content in the phosphorus-copper master alloy is 1.00wt%; the silver content in the silver-copper master alloy is 1.10wt%; the lanthanum content in the lanthanum-yttrium-copper master alloy is 0.75wt% and the yttrium content is 0.60wt%; then the phosphorus-copper master alloy, silver-copper master alloy, lanthanum-yttrium-copper master alloy and 6N5 copper were smelted at 1250℃ for 8h to obtain alloy billets, and finally copper rods with a diameter of 8mm were prepared by directional solidification and continuous casting technology; wherein, the drawing speed is 56m / min.

[0116] (2) Surface treatment: The above-mentioned round copper rods are subjected to surface treatment in sequence. The surface treatment agents are 5wt% sulfuric acid, 5wt% nitric acid, 0.05wt% OP-10 agent, and the remainder is pure water.

[0117] (3) First annealing: The surface-treated copper rod is homogenized and annealed under vacuum conditions; the annealing temperature is 550℃ and the annealing time is 4.5h.

[0118] (4) Rolling (continuous rolling): The annealed copper rod is rolled (continuous rolling) to continuously roll the copper rod with a diameter of 8.0 mm to a diameter of 4.3 mm, with an elongation of 18%-20%.

[0119] (5) Secondary annealing: The rolled copper rod is annealed at 450°C for 2.5 hours under nitrogen protection (purity of 99.9999%), and then forged twice to a copper wire with a diameter of 2.03 mm; specifically: Ø4.3 mm-Ø3.0 mm-Ø2.03 mm.

[0120] (6) Peeling and non-destructive testing: Peel the copper wire after rotary forging to a diameter of 2.00 mm, and then perform non-destructive testing. The peeling speed is 16 m / min and the back tension is 180 N.

[0121] (7) Continuous drawing and retraction: The stripped copper wire is drawn twice to a diameter of 0.10 mm; specifically:

[0122] First step: drawing to a diameter of 0.38 mm, with an elongation of 15%-18%, a speed of 300 m / min, a drawing solution concentration of 1.6 wt%, and an annealing temperature of 380℃;

[0123] Second step: drawing to a diameter of 0.1 mm, with an elongation of 13%-16%, a speed of 400 m / min, a drawing solution concentration of 1.2 wt%, and an annealing temperature of 360 ℃.

[0124] (8) Degreasing and polishing: The copper wire after continuous drawing and retraction is degreasing and polishing; the polishing agent is: 12wt% sodium hydroxide, 20wt% sodium phosphate, 12wt% sodium carbonate, 2wt% OP-10 agent, the bath temperature is 45±5℃, and the rest is water.

[0125] (9) Wire drawing with a zero-slip wire drawing machine: The degreased and polished copper wire is drawn three times to a diameter of 0.01986 mm; specifically:

[0126] First stage: drawing to a diameter of 0.05716 mm; with an elongation of 10%-13%, a speed of 600 m / min, and a drawing solution concentration of 2.2 wt%.

[0127] Second stage: drawing to a diameter of 0.03559 mm; with an elongation of 8%-10%, a speed of 800 m / min, and a drawing solution concentration of 1.8 wt%.

[0128] The third step: drawing the wire to a diameter of 0.01986 mm; with an elongation of 8%-9%, a speed of 1000 m / min, and a drawing solution concentration of 1.1 wt%.

[0129] (10) After the drawing process is completed, the wire is annealed three times in a vertical annealing machine. The annealing temperature is 420℃, the annealing time is 0.35s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, the bonded copper wire is obtained.

[0130] (11) The bonding copper wire is inspected, spun, packaged, stored and shipped.

[0131] Example 2

[0132] like Figure 1 As shown, this embodiment provides a method for preparing bonding copper wire, including the following steps:

[0133] The composition of the bonded copper wire is as follows: phosphorus 42ppm, silver 38ppm, lanthanum 8ppm, yttrium 8ppm, with the balance being copper.

[0134] (1) Preparation of master alloys: 6N5 copper and phosphorus, 6N5 copper and silver, 6N5 copper, lanthanum and yttrium were smelted at 1300℃, 1350℃ and 1550℃ for 6h, 4h and 5h respectively to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy; wherein, by mass percentage, the phosphorus content in the phosphorus-copper master alloy is 1wt%; the silver content in the silver-copper master alloy is 1.1wt%; the lanthanum content in the lanthanum-yttrium-copper master alloy is 0.75wt% and the yttrium content is 0.6wt%; then the phosphorus-copper master alloy, silver-copper master alloy, lanthanum-yttrium-copper master alloy and 6N5 copper were smelted at 1200℃ for 10h to obtain alloy billets, and finally copper rods with a diameter of 8mm were prepared by directional solidification and continuous casting technology; wherein, the drawing speed is 50m / min.

[0135] (2) Surface treatment: The above-mentioned round copper rods are subjected to surface treatment in sequence. The surface treatment agents are 7wt% sulfuric acid, 3wt% nitric acid, 0.03wt% OP-10 agent, and the remainder is pure water.

[0136] (3) First annealing: The surface-treated copper rod is homogenized and annealed under vacuum conditions; the annealing temperature is 600℃ and the annealing time is 4.2h.

[0137] (4) Rolling (continuous rolling): The annealed copper rod is rolled (continuous rolling) to continuously roll the copper rod with a diameter of 8.0 mm to a diameter of 4.3 mm, with an elongation of 18%-20%.

[0138] (5) Secondary annealing: The rolled copper rod is annealed at 425°C for 2 hours under nitrogen protection (purity of 99.9999%), and then forged twice to a copper wire with a diameter of 2.03 mm; specifically: Ø4.3 mm-Ø3.0 mm-Ø2.03 mm.

[0139] (6) Peeling and non-destructive testing: Peel the copper wire after rotary forging to a diameter of 2.00 mm, and then perform non-destructive testing. The peeling speed is 18 m / min and the back tension is 165 N.

[0140] (7) Continuous drawing and retraction: The stripped copper wire is drawn twice to a diameter of 0.1mm; specifically:

[0141] First step: drawing to a diameter of 0.38 mm, with an elongation of 15%-18%, a speed of 350 m / min, a drawing solution concentration of 2.0 wt%, and an annealing temperature of 350℃;

[0142] Second step: drawing to a diameter of 0.1 mm, with an elongation of 13%-16%, a speed of 500 m / min, a drawing solution concentration of 1 wt%, and an annealing temperature of 340℃.

[0143] (8) Degreasing and polishing: The copper wire after continuous pulling and retraction is degreasing and polishing; the polishing agent is: 15wt% sodium hydroxide, 23wt% sodium phosphate, 10wt% sodium carbonate, 1wt% OP-10 agent, the bath temperature is 45℃±5℃, and the rest is water.

[0144] (9) Wire drawing with a zero-slip wire drawing machine: The degreased and polished copper wire is drawn three times to a diameter of 0.01986 mm; specifically:

[0145] First stage: drawing to a diameter of 0.05716 mm; with an elongation of 10%-13%, a speed of 550 m / min, and a drawing solution concentration of 2.5 wt%.

[0146] Second stage: drawing to a diameter of 0.03559 mm; with an elongation of 8%-10%, a speed of 750 m / min, and a drawing solution concentration of 2.0 wt%.

[0147] The third step: drawing the wire to a diameter of 0.01986 mm; with an elongation of 8%-9%, a speed of 950 m / min, and a drawing solution concentration of 1.5 wt%.

[0148] (10) After the drawing process is completed, the wire is annealed three times in a vertical annealing machine. The annealing temperature is 380℃, the annealing time is 0.3s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, the bonded copper wire is obtained.

[0149] (11) The bonding copper wire is inspected, spun, packaged, stored and shipped.

[0150] Example 3

[0151] like Figure 1 As shown, this embodiment provides a method for preparing bonding copper wire, including the following steps:

[0152] The composition of the bonded copper wire is as follows: phosphorus 48ppm, silver 32ppm, lanthanum 12ppm, yttrium 8ppm, with the balance being copper.

[0153] (1) Preparation of master alloys: 6N5 copper and phosphorus, 6N5 copper and silver, 6N5 copper, lanthanum and yttrium were smelted at 1250℃, 1400℃ and 1500℃ for 5h, 6h and 4h respectively to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy; wherein, by mass percentage, the phosphorus content in the phosphorus-copper master alloy is 1.5wt%; the silver content in the silver-copper master alloy is 0.8wt%; the lanthanum content in the lanthanum-yttrium-copper master alloy is 1.5wt% and the yttrium content is 0.8wt%; then the phosphorus-copper master alloy, silver-copper master alloy, lanthanum-yttrium-copper master alloy and 6N5 copper were smelted at 1225℃ for 8h to obtain alloy billets, and finally copper rods with a diameter of 8mm were prepared by directional solidification and continuous casting technology; wherein, the drawing speed is 60m / min.

[0154] (2) Surface treatment: The above-mentioned round copper rods are subjected to surface treatment in sequence. The surface treatment agents are 3wt% sulfuric acid, 7wt% nitric acid, 0.07wt% OP-10 agent, and the remainder is pure water.

[0155] (3) First annealing: The surface-treated copper rod is homogenized and annealed under vacuum conditions; the annealing temperature is 500℃ and the annealing time is 5h.

[0156] (4) Rolling (continuous rolling): The annealed copper rod is rolled (continuous rolling) to continuously roll the copper rod with a diameter of 8.0 mm to a diameter of 4.3 mm, with an elongation of 18%-20%.

[0157] (5) Secondary annealing: The rolled copper rod is annealed at 400℃ for 3 hours under nitrogen protection (purity of 99.9999%), and then forged twice to a copper wire with a diameter of 2.03mm; specifically: Ø4.3mm-Ø3.0mm-Ø2.03mm.

[0158] (6) Peeling and non-destructive testing: Peel the copper wire after rotary forging to a diameter of 2.00 mm, and then perform non-destructive testing. The peeling speed is 20 m / min and the back tension is 150 N.

[0159] (7) Continuous drawing and retraction: The stripped copper wire is drawn twice to a diameter of 0.10 mm; specifically:

[0160] First step: drawing to a diameter of 0.38 mm, with an elongation of 15%-18%, a speed of 400 m / min, a drawing solution concentration of 1.8 wt%, and an annealing temperature of 400℃;

[0161] Second step: drawing to a diameter of 0.1 mm, with an elongation of 13%-16%, a speed of 300 m / min, a drawing solution concentration of 1.5 wt%, and an annealing temperature of 390℃.

[0162] (8) Degreasing and polishing: The copper wire after continuous pulling and retraction is degreasing and polishing; the polishing agent is: 10wt% sodium hydroxide, 18wt% sodium phosphate, 15wt% sodium carbonate, 3wt% OP-10 agent, the bath temperature is 40℃±5℃, and the rest is water.

[0163] (9) Wire drawing with a zero-slip wire drawing machine: The degreased and polished copper wire is drawn three times to a diameter of 0.01986 mm; specifically:

[0164] First stage: drawing to a diameter of 0.05716 mm; with an elongation of 10%-13%, a speed of 650 m / min, and a drawing solution concentration of 2.0 wt%.

[0165] Second stage: drawing to a diameter of 0.03559 mm; with an elongation of 8%-10%, a speed of 850 m / min, and a drawing solution concentration of 1.5 wt%.

[0166] The third step: drawing the wire to a diameter of 0.01986 mm; with an elongation of 8%-9%, a speed of 1050 m / min, and a drawing solution concentration of 1.0 wt%.

[0167] (10) After the drawing process is completed, the wire is annealed three times in a vertical annealing machine. The annealing temperature is 450℃, the annealing time is 0.4s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, the bonded copper wire is obtained.

[0168] (11) The bonding copper wire is inspected, spun, packaged, stored and shipped.

[0169] Comparative Example 1

[0170] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1. The only difference is that the continuous rolling-spinning-stripping steps in steps (4)-(6) are replaced by conventional drawing, and the wire is drawn to a diameter of 1.952 mm, a speed of 200 m / min, a drawing fluid concentration of 2.0 wt%, and an elongation of 10%-20%.

[0171] Comparative Example 2

[0172] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1. The only difference is that the continuous drawing and annealing step (7) is replaced with a conventional drawing method, specifically including: drawing a copper rod with a diameter of 2.0 mm to obtain a copper wire with a diameter of 0.1039 mm at a speed of 200 m / min, a drawing liquid concentration of 2.0 wt%, an elongation of 14%-22%, without intermediate annealing heat treatment, and performing annealing treatment at a diameter of 0.1039 mm at a temperature of 400℃.

[0173] Comparative Example 3

[0174] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1, except that step (9) of the non-slip wire drawing machine is replaced with a conventional drawing method.

[0175] Comparative Example 4

[0176] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1, except that silver is replaced with copper.

[0177] Comparative Example 5

[0178] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1, except that lanthanum is replaced with copper.

[0179] Comparative Example 6

[0180] This comparative example provides a method for preparing bonded copper wire, which is basically the same as the steps in Example 1, except that yttrium is replaced with copper.

[0181] Experimental Example 1

[0182] The first continuous pull-and-pull test was conducted on Example 1, which had undergone the stripping treatment, and Comparative Example 1, which had not undergone the stripping treatment. The number of wire breaks was recorded. Specifically, the copper wire with a diameter of 2.00 mm was drawn to a diameter of 0.38 mm and then pulled for 5000 m. The number of wire breaks during this process was recorded. The results are shown in the table below.

[0183] Table 1. Number of wire breaks in Example 1 and Comparative Example 1 during the first continuous pull-and-retract process.

[0184]

[0185] As can be seen from the table above, Comparative Example 1 experienced a higher number of wire breaks during the first continuous drawing and unwinding process, while Embodiment 1 of the present invention, through continuous rolling-spinning-stripping steps, significantly improved the machinability of the copper wire and effectively reduced the number of wire breaks.

[0186] Meanwhile, compared with the traditional bonding copper wire drawing process, rolling and rotary forging can significantly improve production efficiency. It takes about 6 hours to draw an 8mm copper casting rod to 2.03mm using the traditional die drawing process, but it only takes about 1 hour to roll and rotary forge to 2.03mm. At the same time, rolling and rotary forging do not involve the use of dies, which can save costs for enterprises.

[0187] Experimental Example 2

[0188] According to GB / T10573-2020 "Tension Test Method for Non-ferrous Metal Wires", the bonding copper wires prepared in Example 1 and Comparative Example 2 were tested for breaking force and elongation using an IMS-W101 (INSTRON1kN) tensile tester. The results are shown in the table below.

[0189] Table 2. Test results of bonding copper wire performance in Example 1 and Comparative Example 2

[0190]

[0191] As can be seen from the table above, the bonding copper wires of this invention, which adopt a continuous pulling and unpulling method, have more stable mechanical properties and higher consistency, laying a good foundation for improving the overall quality of the product. At the same time, Example 1, through the continuous pulling and unpulling method, can realize a continuous production process, reduce waiting time and changeover time in the production process, improve production efficiency, and ensure that the temperature and speed are constant throughout the entire production process, thus ensuring the stability and consistency of product quality.

[0192] Experimental Example 3

[0193] The bonding copper wires prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to the following performance tests, and the results are shown in the table below:

[0194] (1) Tensile strength and elongation test: Refer to GB / T10573-2020 "Tension test method for non-ferrous metal wires";

[0195] (2) Single-axis drawing length test method: The bonding copper wire is drawn from 0.10mm to 0.020mm. There is no upper limit on the length of the single axis. The wire is drawn until it breaks naturally during the drawing process. The length of the bonding copper wire drawn from each axis is 0.020mm.

[0196] (3) The surface morphology and microstructure of the cast rod cross section were observed using a scanning electron microscope. A porosity analysis method was created, with a full score of 36 points. The scoring parameters included porosity size and number. The higher the value, the smaller the porosity volume ratio, which means that the density of the cast billet is higher.

[0197] (4) Reliability testing: Before the test, the electrical parameters and appearance of the sample are tested and inspected to ensure that the electrical parameters of the sample are qualified and the appearance is normal; at low temperature -55℃ (+0, -10) and high temperature +125℃ (+15, -0), 30 minutes is one cycle (15 minutes each for high and low temperature), the switching time does not exceed 30 seconds, and the electrical performance and appearance are tested once every 100 cycles;

[0198] (5) Resistivity test: According to GB / T3048.4-2007 "Test methods for electrical properties of wires and cables - Part 4: DC resistance test of conductors".

[0199] Table 3. Performance test results of the bonding copper wires prepared in each embodiment and comparative example.

[0200]

[0201] As can be seen from the table above, the bonded copper wires prepared in Examples 1-3 of this invention have longer elongation, higher breaking force, longer uniaxial drawing length, higher casting porosity score, and better reliability and resistivity. Furthermore, the addition of trace elements silver, lanthanum, and yttrium in this invention plays a positive role in improving the mechanical properties and reliability of the bonded copper wires, making them promising for applications in microelectronics packaging and semiconductor manufacturing. Compared with Comparative Example 1, the addition of rolling and rotary forging deformation processes in these examples effectively improves the mechanical properties of the bonded copper wires. Continuous rolling significantly reduces the thickness of the metal material, thereby reducing its weight and increasing strength, enabling it to withstand larger loads and pressures. Rotary forging is a low-energy, multi-stage deformation process that can increase strength while reducing internal porosity. Compared to Comparative Example 2, the application of continuous drawing and annealing process can effectively improve the consistency between product batches. Furthermore, the immediate annealing treatment after metal drawing can better eliminate or reduce structural defects and residual stress, refine the grain structure, and restore plasticity, thereby improving the mechanical properties and reliability of the product. Compared to Comparative Example 3, the application of non-slip wire drawing technology can significantly reduce the occurrence of slippage during the wire drawing process, ensuring the stability and consistency of the wire drawing operation, preventing stress concentration and uneven deformation caused by slippage, and thus promoting the homogenization and densification of the internal structure of the bonded wire. When subjected to tensile force, the stress is more evenly distributed, significantly enhancing its tensile strength. In addition, non-slip wire drawing technology also enhances the uniform deformation ability of the bonded wire during the stretching process by avoiding local deformation and damage caused by slippage, enabling the bonded wire to withstand greater deformation during the stretching process without easily breaking, thereby significantly improving its elongation. Figure 2The images show a comparison of the surface quality of Example 1 and Comparative Example 3 (magnification 3000x). It can be seen that Example 1, using a slip-free drawing process, significantly improves the surface quality of the wire, resulting in no scratches and a smoother surface. In Comparative Example 4, the absence of silver significantly reduces the reliability of the bonded copper wire. This is because the addition of silver improves the heat dissipation performance of the copper wire, allowing it to dissipate heat more effectively at high temperatures and maintain stable performance. In Comparative Example 5, the absence of lanthanum reduces all properties of the bonded copper wire. This is because lanthanum inhibits recrystallization nucleation and growth, and works in conjunction with phosphorus to refine the grain structure, enhancing the mechanical properties of the bonded copper wire. In Comparative Example 6, the absence of yttrium significantly increases the resistivity of the bonded copper wire, hindering the transmission of electrical signals. This is because the addition of yttrium refines the copper grains, effectively reducing impurities, weakening lattice distortion, reducing electron scattering probability, and further improving conductivity.

[0202] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a bonding copper wire, characterized in that, Includes the following steps: (1) Phosphorus, silver, lanthanum and yttrium are mixed with a portion of high-purity copper and then smelted once to obtain phosphorus-copper master alloy, silver-copper master alloy and lanthanum-yttrium-copper master alloy; (2) The phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper are mixed and then smelted twice to obtain a copper rod with a diameter of 8mm-10mm; (3) The copper rod is annealed once and then continuously rolled to a diameter of 4.2mm-4.4mm; (4) The rolled copper rod is subjected to secondary annealing and then rotary forging to obtain copper wire with a diameter of 2.0mm-2.1mm; (5) The copper wire after rotary forging is subjected to continuous drawing and undrawing wire drawing and zero-difference sliding wire drawing to obtain copper wire with a diameter of 0.018mm-0.030mm; (6) The copper wire is subjected to three annealing processes to obtain the bonding copper wire; The chemical composition of the bonded copper wire includes: phosphorus 42ppm-48ppm, silver 32ppm-38ppm, lanthanum 8ppm-12ppm, yttrium 8ppm-12ppm, and balance copper; The bonding copper wire has a breaking strength ≥7.5cN, an elongation of 11.0%-15.0%, and a reliability ≥300 cycles.

2. The method for preparing the bonding copper wire according to claim 1, characterized in that, In the continuous rolling step, the elongation is 18%-20%; And / or, the number of rotary forgings includes at least two times; in the first rotary forging, the diameter is forged to 2.9mm-3.1mm, and in the second rotary forging, the diameter is forged to 2.0mm-2.1mm.

3. The method for preparing the bonding copper wire according to claim 1, characterized in that, The annealing temperature is 500℃-600℃, and the annealing time is 4h-5h; the annealing is carried out under vacuum conditions. And / or, the temperature of the secondary annealing is 400℃-500℃, the secondary annealing time is 2h-3h, and the annealing atmosphere is an inert atmosphere; And / or, the three annealing temperatures are 380℃-450℃, the three annealing times are 0.3s-0.4s, and the annealing atmosphere is a nitrogen and hydrogen atmosphere.

4. The method for preparing the bonding copper wire according to claim 1, characterized in that, The phosphorus content in the phosphorus-copper master alloy is 1.0wt%-1.5wt%. And / or, in the silver-copper master alloy, the silver content is 0.8wt%-1.1wt%; And / or, in the lanthanum-yttrium-copper master alloy, the lanthanum content is 0.75wt%-1.5wt%, and the yttrium content is 0.6wt%-0.8wt%; And / or, the temperature of the first melting is 1000℃-1600℃, and the time is 4h-6h; And / or, the secondary melting temperature is 1200℃-1250℃, and the time is 8h-10h.

5. The method for preparing the bonding copper wire according to claim 1, characterized in that, The continuous pull and retraction step includes at least two steps; In the first continuous drawing and undrawing process, the wire is drawn and undrawn to a diameter of 0.3mm-0.4mm, an elongation of 15%-18%, a speed of 300m / min-400m / min, a drawing solution concentration of 1.5wt%-2.0wt%, and an annealing temperature of 350℃-400℃. In the second continuous drawing and annealing process, the wire is drawn and annealed to a diameter of 0.08mm-0.12mm, an elongation of 13%-16%, a speed of 300m / min-500m / min, a drawing solution concentration of 1.0wt%-1.5wt%, and an annealing temperature of 340℃-390℃. And / or, the zero-difference wire drawing step includes at least three steps; In the first zero-difference drawing process, the wire is drawn to a diameter of 0.05mm-0.06mm, with an elongation of 10%-13%, at a speed of 550m / min-650m / min, and the drawing solution concentration is 2.0wt%-2.5wt%. In the second zero-difference drawing process, the wire is drawn to a diameter of 0.03mm-0.04mm, with an elongation of 8%-10%, at a speed of 750m / min-850m / min, and the drawing solution concentration is 1.5wt%-2.0wt%. In the third zero-difference drawing process, the wire is drawn to a diameter of 0.01mm-0.02mm, with an elongation of 8%-9%, a speed of 950m / min-1050m / min, and a drawing solution concentration of 1.0wt%-1.5wt%.

6. The method for preparing the bonding copper wire according to claim 1, characterized in that, After the secondary melting, it also includes directional solidification and continuous casting steps; And / or, it also includes a step of sequentially performing surface treatment on the copper rod; The surface treatment agent includes: 3wt%-7wt% sulfuric acid, 3wt%-7wt% nitric acid, 0.03wt%-0.07wt% OP-10 agent, and the remainder is purified water; And / or, it also includes the step of sequentially peeling and non-destructive testing of the copper wire after rotary forging, wherein the diameter of the copper wire after peeling is 1.8mm-2.2mm; The peeling speed is 15m / min-20m / min, and the back tension is 150N-180N; And / or, it also includes a degreasing and polishing process for the drawn copper wire; The degreasing and polishing treatment temperature is 40℃-50℃; And / or, the polishing agent comprises: 10wt%-15wt% sodium hydroxide, 18wt%-23wt% sodium phosphate, 10wt%-15wt% sodium carbonate, 1wt%-3wt% OP-10 agent, and the remainder is water; And / or, in step (2), the drawing speed in continuous casting is 50m / min-60m / min.

7. The application of the bonding copper wire prepared by the preparation method according to any one of claims 1-6 in electronic packaging.

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