Bonding copper wire and preparation method and application thereof

Abstract

The invention relates to the technical field of bonding wires for semiconductor packaging, and discloses a bonding copper wire and a preparation method and application thereof. The bonding copper wire comprises the following chemical components in percentage by weight: 42 ppm to 48 ppm of phosphorus, 32 ppm to 38 ppm of silver, 8 ppm to 12 ppm of lanthanum, 8 ppm to 12 ppm of yttrium and the balance of copper. The tensile strength of the bonding copper wire is greater than or equal to 7.5 cN, the elongation is 11.0%-15%, and the reliability is greater than or equal to 300 cycles. 8 ppm to 12 ppm of lanthanum element, 8 ppm to 12 ppm of yttrium element, 32 ppm to 38 ppm of silver element and 42 ppm to 48 ppm of phosphorus element are added into the bonding copper wire, a synergistic effect is achieved among multi-element microalloying, the corrosion-resistant welding effect better than that of a single element can be achieved, and the comprehensive performance of the alloy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bonding wires for semiconductor packaging, and in particular to a bonding copper wire and a preparation method and application thereof. Background Art

[0002] As one of the important basic materials for electronic packaging, bonding wire is used to realize the electrical connection between semiconductor chips and pins, and plays the role of importing and exporting current and signals between chips and the outside world. At present, 80% of the packages on the market are bonded and packaged with wires, and the performance of bonding wire will directly affect the performance of IC chips. With the development trend of miniaturization, modularization and high integration of electronic products, bonding wire is required to have better mechanical properties and processing performance. Compared with gold wire and aluminum wire, copper has obvious cost advantages, and also has excellent electrical conductivity, thermal conductivity, low hardness and good chemical stability, so it is a strong competitor in the packaging market.

[0003] The conventional copper-based wire preparation method is to prepare a rod blank first, and then go through multiple rough drawing, medium drawing, and micro drawing. After plastic deformation, the internal grains interact with each other and rotate relative to the external force axis. Most of the grains gather in certain orientations to form a deformed texture. The rotation of the crystals during the stretching process makes the slip direction parallel to the single tensile axis, and the mechanical properties and surface tension are limited, resulting in poor mechanical properties of the bonding copper wire, low reliability, low production efficiency, cumbersome processing steps and high cost. At present, the main elements of copper wire alloying are Ag, Pd, and Ca. The addition of these elements can effectively improve the oxidation resistance and ductility of pure copper, but there are still defects such as poor mechanical properties and low reliability.

[0004] Therefore, how to obtain bonding copper wire 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 a bonding copper wire with good mechanical properties and high reliability.

[0006] The invention also provides a method for preparing the 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 comprises, by weight percentage: 42ppm-48ppm phosphorus, 32ppm-38ppm silver, 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, and the balance copper;

[0008] The breaking force of the bonding copper wire is ≥7.5 cN, the elongation is 11.0%-15.0%, and the reliability is ≥300 cycles.

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

[0010] The breaking force of the bonding copper wire is ≥7.6 cN, and the elongation is 11.5%-12%.

[0011] In an 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 breaking force of the bonding copper wire is 7.9 cN, and the elongation is 11.6%.

[0013] In a second aspect, the present invention further provides a method for preparing the above-mentioned bonding copper wire, comprising the following steps:

[0014] (1) mixing phosphorus, silver, lanthanum and yttrium with a portion of high-purity copper respectively and then smelting them once to obtain a phosphorus-copper master alloy, a silver-copper master alloy and a lanthanum-yttrium-copper master alloy;

[0015] (2) mixing the phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper and then performing secondary smelting to obtain a copper rod with a diameter of 8 mm to 10 mm;

[0016] (3) subjecting the copper rod to an annealing treatment, and then continuously rolling the copper rod to a diameter of 4.2 mm to 4.4 mm;

[0017] (4) performing secondary annealing on the rolled copper rod, and then performing rotary forging to obtain a copper wire with a diameter of 2.0 mm to 2.1 mm;

[0018] (5) performing continuous drawing and continuous withdrawal wire drawing and zero-slip wire drawing on the rotary forged copper wire to obtain a copper wire with a diameter of 0.018 mm to 0.030 mm;

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

[0020] In an optional embodiment, in the continuous calendering step, the elongation is 18%-20%.

[0021] In an optional embodiment, the number of rotary forgings includes at least 2 times; in the first rotary forging, the diameter is rotary forged to 2.9mm-3.1mm; in the second rotary forging, the diameter is rotary forged to 2.0mm-2.1mm.

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

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

[0024] In an optional embodiment, the temperature of the third annealing is 380° C.-450° C., the time of the second annealing is 0.3 s-0.4 s; and the annealing atmosphere is a nitrogen and hydrogen atmosphere.

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

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

[0027] In an optional embodiment, in the lanthanum-yttrium-copper master alloy, the content of lanthanum is 0.75wt%-1.5wt%, and the content of yttrium is 0.6wt%-0.8wt%.

[0028] In an optional embodiment, the primary smelting is performed at a temperature of 1000°C-1600°C and for a time of 4h-6h.

[0029] In an optional embodiment, the secondary smelting is carried out at a temperature of 1200° C.-1250° C. and for a time of 8 h-10 h.

[0030] In an optional embodiment, the continuous pulling and retracting steps are included at least twice.

[0031] In an optional embodiment, in the first continuous drawing and retreating, the wire is drawn and retreated to a diameter of 0.3mm-0.4mm, an elongation of 15%-18%, a speed of 300m / min-400m / min, a concentration of the drawing liquid of 1.5wt%-2.0wt%, and an annealing temperature of 350°C-400°C.

[0032] In an optional embodiment, in the second continuous drawing and retreating, the continuous drawing and retreating is performed to a diameter of 0.08mm-0.12mm, an elongation of 13%-16%, a speed of 300m / min-500m / min, a drawing liquid concentration of 1.0wt%-1.5wt%, and an annealing temperature of 340°C-390°C.

[0033] In an optional embodiment, the step of seamless wire drawing includes at least three times.

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

[0035] In an optional embodiment, in the second differential slip wire drawing, the wire is drawn to a diameter of 0.03 mm-0.04 mm, an elongation of 8%-10%, a speed of 750 m / min-850 m / min, and a drawing liquid concentration of 1.5 wt%-2.0 wt%.

[0036] In an optional embodiment, in the third differential sliding wire drawing, the wire drawing is performed to a diameter of 0.01 mm-0.02 mm, an elongation of 8%-9%, a speed of 950 m / min-1050 m / min, and a drawing liquid concentration of 1.0 wt%-1.5 wt%.

[0037] In an optional embodiment, after the secondary smelting, directional solidification and continuous casting steps are also included.

[0038] In an optional embodiment, the method further includes performing surface treatment steps on the copper rod in sequence.

[0039] In an optional embodiment, the surface treatment agent includes: 3wt%-7wt% sulfuric acid, 3wt%-7wt% nitric acid, 0.03wt%-0.07wt% OP-10 agent, and the rest is pure water.

[0040] In an optional embodiment, the copper wire after rotary forging is subjected to peeling treatment and non-destructive testing steps in sequence, and the diameter of the copper wire after peeling is 1.8mm-2.2mm.

[0041] In an optional embodiment, the peeling speed is 15m / min-20m / min, and the post-tensioning force is 150N-180N.

[0042] In an optional embodiment, the method further includes performing a degreasing and polishing step on the copper wire after drawing.

[0043] In an optional embodiment, the degreasing and polishing treatment temperature is 40°C-50°C.

[0044] In an optional embodiment, the polishing agent includes: 10wt%-15wt% sodium hydroxide, 18wt%-23wt% sodium phosphate, 10wt%-15wt% sodium carbonate, 1wt%-3wt% OP-10 agent, and the rest is water.

[0045] In an optional embodiment, in step (2), the drawing speed during the continuous casting process is 50m / min-60m / min.

[0046] In a third aspect, the present invention further 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 the present invention has the chemical composition of: 42ppm-48ppm phosphorus, 32ppm-38ppm silver, 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, and the balance copper; the breaking force of the bonding copper wire is ≥7.5cN, the elongation is 11.0%-15.0%, and the reliability is ≥300 cycles. The present invention adds 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, 32ppm-38ppm silver, and 42ppm-48ppm phosphorus to the bonding copper wire. There is a synergistic effect between the multi-element micro-alloying, which can exert a better anti-corrosion welding effect than a single element and improve the comprehensive performance of the alloy; specifically, adding phosphorus to high-purity copper can eliminate oxygen in the copper alloy without affecting the electrical conductivity and thermal conductivity; adding yttrium can refine the copper grains, effectively reduce impurities in copper, weaken lattice distortion, reduce the probability of electron scattering, and further improve the electrical conductivity. High; adding lanthanum can inhibit the nucleation and growth of recrystallization, and can cooperate with phosphorus to promote the refinement of grain structure and enhance the mechanical properties of finished bonding copper wire; at the same time, lanthanum can also effectively improve the ball formation in the bonding process; adding silver can form solid solution with the copper matrix or form intermetallic compounds. These interface structures and phase change processes can improve the mechanical strength and corrosion resistance of the bonding 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, so that it can dissipate heat more effectively in a high temperature environment, maintain stable performance, and improve its reliability.

[0049] 2. The preparation method of the bonding copper wire provided by the present invention comprises the following steps: mixing phosphorus, silver, lanthanum and yttrium with part of high-purity copper respectively and then smelting once to obtain phosphorus-copper intermediate alloy, silver-copper intermediate alloy and lanthanum-yttrium-copper intermediate alloy; mixing the phosphorus-copper intermediate alloy, the silver-copper intermediate alloy and the lanthanum-yttrium-copper intermediate alloy with the remaining high-purity copper and then smelting twice to obtain a copper rod with a diameter of 8mm-10mm; annealing the copper rod once and then continuously rolling it to a diameter of 4.2mm-4.4mm; annealing the rolled copper rod twice and then rotary forging to obtain a copper wire with a diameter of 2.0mm-2.1mm; performing continuous drawing and continuous withdrawal wire drawing and zero-slip wire drawing on the rotary forged copper wire to obtain a copper wire with a diameter of 0.018mm-0.030mm; annealing the copper wire three times to obtain the bonding copper wire. Since the content of added elements lanthanum, yttrium and silver and phosphorus is small, the amount of addition is difficult to control. If they are directly smelted with copper, the uniformity of the cast rods will be poor. The present invention first obtains an intermediate alloy through a primary smelting, and then smelts it twice with the remaining high-purity copper to better ensure the uniform fusion of the added elements and the matrix copper elements, thereby ensuring the uniformity of the bonding copper wire. After a primary annealing treatment, various structural defects and residual stresses caused by the copper rod during the rolling process can be improved or eliminated, and the workpiece can be softened for subsequent processing. The grains can also be refined, and the structure can be improved to improve the mechanical properties of the workpiece, preparing for the third annealing treatment. After continuous rolling, the thickness of the metal material can be significantly reduced to achieve the effect of reducing its own weight, and the tensile strength is significantly improved, the yield strength is also increased, and the elongation is reduced, which has a significant effect on the improvement of strength. After the secondary annealing, the strength first decreases and then stabilizes, with a consistent overall trend, a dense organizational structure, fine grains, and a relatively uniform precipitated phase. The rotary forging step can refine the grains, eliminate internal micropores, improve the mechanical properties and electrical conductivity, and reduce the pores inside the material; the continuous drawing and annealing treatment can effectively improve the consistency between product batches; the non-slip wire drawing process can significantly reduce the incidence of sliding during the wire drawing process, ensure the stability and consistency of the wire drawing operation, prevent stress concentration and uneven deformation caused by sliding, and then promote the homogenization and densification of the internal structure of the bonding copper wire. When subjected to tensile force, the stress is more evenly distributed, and its resistance to breaking is significantly enhanced; in addition, the non-slip wire drawing process also enhances the uniform deformation ability of the bonding copper wire during the stretching process by avoiding local deformation and damage caused by sliding, so that the bonding copper wire can withstand greater deformation during the stretching process without being easily broken, thereby significantly improving its elongation; in summary, the process selection of pressure processing in the present invention is beneficial to the metallographic microstructure of the copper wire, and the elimination of micropores improves the mechanical properties and reliability.

[0050] The present invention makes each element in the alloy evenly distributed through the first annealing, the second annealing and the third annealing, thereby finally improving the mechanical properties of the product.

[0051] 3. The preparation method of the bonding copper wire provided by the present invention optimizes the production process and process parameters of the continuous drawing and annealing process, with an input wire of 2.0mm-2.1mm, an output wire of 0.08mm-0.12mm, a drawing speed of 300m / min-500m / min, and an annealing temperature of 340-400°C, thereby replacing the lengthy and complicated traditional process, greatly shortening the risk of bare copper wire being easily oxidized, reducing energy waste, and reducing the impact of production on the environment, and meeting the requirements of modern industrial production for energy conservation and environmental protection; the annealing temperature is limited during the continuous drawing and annealing process, and the metal is annealed immediately after drawing, which can better eliminate or reduce tissue defects and residual stress, refine tissue grains, and restore plasticity, thereby improving product mechanical properties and reliability.

[0052] 4. Compared with the traditional bonding copper wire drawing process, the preparation method of the bonding copper wire provided by the present invention does not involve the use of molds in calendering and rotary forging, which saves production costs and significantly improves production efficiency; then, through the continuous drawing and retreating steps, the stability and consistency of the bonding copper wire are guaranteed, and the mechanical properties are improved; it can also realize continuous production, reduce the waiting and process change time in the production process, greatly improve production efficiency, and reduce production costs; then, the differential slip wire drawing is carried out, which greatly reduces the friction factor, avoids the sliding friction that may occur in the traditional wire drawing process, improves the accuracy of the bonding copper wire, and ensures the stability of different batches of bonding copper wire.

[0053] 5. The preparation method of the bonding copper wire provided by the present invention also includes a peeling step, which can remove surface defects of the copper wire material 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 consistent, thereby improving the processability and laying the foundation for the stable and consistent breaking force and elongation of the bonding copper wire.

[0054] 6. The preparation method of the bonding copper wire provided by the present invention can perform online non-destructive flaw detection and timely discover hole-like defects remaining on the surface.

[0055] 7. The preparation method of the bonding copper wire provided by the present invention adopts directional solidification and continuous melt-casting technology. The copper rod obtained by directional solidification casting has fewer internal grain boundaries, fewer impurities and bubbles, significantly improves the microstructure of the bonding wire, and further enhances the mechanical properties and reliability of the bonding wire. The continuous melt-casting technology is to change the cold casting mold in the traditional continuous casting into a heated casting mold, thereby avoiding nucleation on the mold wall and completely eliminating equiaxed crystals, so that heat is diffused only in a single direction - the axial direction of the casting billet, to obtain a unidirectionally solidified columnar crystal continuous ingot, control the morphology of the solidification interface and the thermal flow field distribution of the ingot, promote the competitive growth of axial grains, that is, the entire ingot can be gradually controlled by one grain, realize single crystal continuous casting, form a uniform crystal structure, reduce stress concentration inside the material, and thus improve the tensile strength and fatigue life of the bonding wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0058] Figure 2 It is a surface comparison diagram of the bonding copper wires prepared in Example 1 of the present invention and Comparative Example 3. DETAILED DESCRIPTION

[0059] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0060] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0061] The present invention is further described in detail below in conjunction with specific embodiments. These embodiments 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 comprises, by weight percentage: 42ppm-48ppm of phosphorus, 32ppm-38ppm of silver, 8ppm-12ppm of lanthanum, 8ppm-12ppm of yttrium, and the balance of copper;

[0063] The breaking force of the bonding copper wire is ≥7.5 cN, the elongation is 11.0%-15.0%, and the reliability is ≥300 cycles.

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

[0065] The breaking force of the bonding copper wire is ≥7.6 cN, and the elongation is 11.5%-12%.

[0066] In an 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 breaking force of the bonding copper wire is 7.9 cN, and the elongation is 11.6%.

[0068] The present invention adds 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, 32ppm-38ppm silver, and 42ppm-48ppm phosphorus to the bonding copper wire. The multi-element microalloying has a synergistic effect, can exert a better anti-corrosion welding effect than a single element, and improves the comprehensive performance of the alloy; specifically, adding phosphorus to high-purity copper can eliminate oxygen in the copper alloy without affecting the electrical conductivity and thermal conductivity; adding yttrium can refine the copper grains, effectively reduce impurities in the copper, weaken the lattice distortion, reduce the probability of electron scattering, and further improve the electrical conductivity. High; adding lanthanum can inhibit the nucleation and growth of recrystallization, and can cooperate with phosphorus to promote the refinement of grain structure and enhance the mechanical properties of finished bonding copper wire; at the same time, lanthanum can also effectively improve the ball formation in the bonding process; adding silver can form solid solution with the copper matrix or form intermetallic compounds. These interface structures and phase change processes can improve the mechanical strength and corrosion resistance of the bonding 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, so that it can dissipate heat more effectively in a high temperature environment, maintain stable performance, and improve its reliability.

[0069] In a second aspect, the present invention further provides a method for preparing the above-mentioned bonding copper wire, comprising the following steps:

[0070] (1) mixing phosphorus, silver, lanthanum and yttrium with a portion of high-purity copper respectively and then smelting them once to obtain a phosphorus-copper master alloy, a silver-copper master alloy and a lanthanum-yttrium-copper master alloy;

[0071] (2) mixing the phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper and then performing secondary smelting to obtain a copper rod with a diameter of 8 mm to 10 mm;

[0072] (3) subjecting the copper rod to an annealing treatment, and then continuously rolling the copper rod to a diameter of 4.2 mm to 4.4 mm;

[0073] (4) performing secondary annealing on the rolled copper rod, and then performing rotary forging to obtain a copper wire with a diameter of 2.0 mm to 2.1 mm;

[0074] (5) performing continuous drawing and continuous withdrawal wire drawing and zero-slip wire drawing on the rotary forged copper wire to obtain a copper wire with a diameter of 0.018 mm to 0.030 mm;

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

[0076] Since the content of added elements lanthanum, yttrium and silver and phosphorus is small, the amount of addition is difficult to control. If they are directly smelted with copper, the uniformity of the cast rods will be poor. The present invention first obtains an intermediate alloy through a primary smelting, and then smelts it twice with the remaining high-purity copper to better ensure the uniform fusion of the added elements and the matrix copper elements, thereby ensuring the uniformity of the bonding copper wire. After a primary annealing treatment, various structural defects and residual stresses caused by the copper rod during the rolling process can be improved or eliminated, and the workpiece can be softened for subsequent processing. The grains can also be refined, and the structure can be improved to improve the mechanical properties of the workpiece, preparing for the third annealing treatment. After continuous rolling, the thickness of the metal material can be significantly reduced to achieve the effect of reducing its own weight, and the tensile strength is significantly improved, the yield strength is also increased, and the elongation is reduced, which has a significant effect on the improvement of strength. After the secondary annealing, the strength first decreases and then stabilizes, with a consistent overall trend, a dense organizational structure, fine grains, and a relatively uniform precipitated phase. The rotary forging step can refine the grains, eliminate internal micropores, improve the mechanical properties and electrical conductivity, and reduce the pores inside the material; the continuous drawing and annealing treatment can effectively improve the consistency between product batches; the non-slip wire drawing process can significantly reduce the incidence of sliding during the wire drawing process, ensure the stability and consistency of the wire drawing operation, prevent stress concentration and uneven deformation caused by sliding, and then promote the homogenization and densification of the internal structure of the bonding copper wire. When subjected to tensile force, the stress is more evenly distributed, and its resistance to breaking is significantly enhanced; in addition, the non-slip wire drawing process also enhances the uniform deformation ability of the bonding copper wire during the stretching process by avoiding local deformation and damage caused by sliding, so that the bonding copper wire can withstand greater deformation during the stretching process without being easily broken, thereby significantly improving its elongation; in summary, the process selection of pressure processing in the present invention is beneficial to the metallographic microstructure of the copper wire, and the elimination of micropores improves the mechanical properties and reliability.

[0077] The present invention makes each element in the alloy evenly distributed through the first annealing, the second annealing and the third annealing, thereby finally improving the mechanical properties of the product.

[0078] In an optional embodiment, in the continuous calendering step, the elongation is 18%-20%.

[0079] In an optional embodiment, the number of rotary forgings includes at least 2 times; in the first rotary forging, the diameter is rotary forged to 2.9mm-3.1mm; in the second rotary forging, the diameter is rotary forged to 2.0mm-2.1mm.

[0080] Compared with the traditional bonding copper wire drawing process, the calendering and rotary forging of the present invention do not involve the use of molds, save production costs, and significantly improve production efficiency; then, through the continuous drawing and retreating steps, the stability and consistency of the bonding copper wire are guaranteed, and the mechanical properties are improved; continuous production can also be achieved, and the waiting and process change time in the production process can be reduced, which greatly improves production efficiency and reduces production costs; then, differential sliding wire drawing is performed, which greatly reduces the friction factor, avoids the sliding friction that may occur in the traditional wire drawing process, improves the accuracy of the bonding copper wire, and ensures the stability of different batches of bonding copper wire.

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

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

[0083] In an optional embodiment, the temperature of the third annealing is 380° C.-450° C., the time of the second annealing is 0.3 s-0.4 s; and the annealing atmosphere is a nitrogen and hydrogen atmosphere.

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

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

[0086] In an optional embodiment, in the lanthanum-yttrium-copper master alloy, the content of lanthanum is 0.75wt%-1.5wt%, and the content of yttrium is 0.6wt%-0.8wt%.

[0087] In an optional embodiment, the primary smelting is performed at a temperature of 1000°C-1600°C and for a time of 4h-6h.

[0088] In an optional embodiment, the secondary smelting is carried out at a temperature of 1200° C.-1250° C. and for a time of 8 h-10 h.

[0089] In an optional embodiment, the continuous pulling and retracting steps are included at least twice.

[0090] In an optional embodiment, in the first continuous drawing and retreating, the wire is drawn and retreated to a diameter of 0.3mm-0.4mm, an elongation of 15%-18%, a speed of 300m / min-400m / min, a concentration of the drawing liquid of 1.5wt%-2.0wt%, and an annealing temperature of 350°C-400°C.

[0091] In an optional embodiment, in the second continuous drawing and retreating, the continuous drawing and retreating is performed to a diameter of 0.08mm-0.12mm, an elongation of 13%-16%, a speed of 300m / min-500m / min, a drawing liquid concentration of 1.0wt%-1.5wt%, and an annealing temperature of 340°C-390°C.

[0092] The present invention optimizes the production process and process parameters of the continuous drawing and annealing process, with an inlet wire of 2.0mm-2.1mm, an outlet wire of 0.08mm-0.12mm, a drawing speed of 300m / min-500m / min, and an annealing temperature of 340-400°C, thereby replacing the lengthy and complicated traditional process, greatly shortening the risk of bare copper wire being easily oxidized, reducing energy waste, and reducing the impact of production on the environment, thereby meeting the requirements of modern industrial production for energy conservation and environmental protection; and limiting the annealing temperature during the continuous drawing and annealing process, and immediately subjecting the metal to annealing treatment after drawing, which can better eliminate or reduce tissue defects and residual stress, refine tissue grains, and restore plasticity, thereby improving the mechanical properties and reliability of the product.

[0093] In an optional embodiment, the step of seamless wire drawing includes at least three times.

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

[0095] In an optional embodiment, in the second differential slip wire drawing, the wire is drawn to a diameter of 0.03 mm-0.04 mm, an elongation of 8%-10%, a speed of 750 m / min-850 m / min, and a drawing liquid concentration of 1.5 wt%-2.0 wt%.

[0096] In an optional embodiment, in the third differential sliding wire drawing, the wire drawing is performed to a diameter of 0.01 mm-0.02 mm, an elongation of 8%-9%, a speed of 950 m / min-1050 m / min, and a drawing liquid concentration of 1.0 wt%-1.5 wt%.

[0097] In an optional embodiment, after the secondary smelting, directional solidification and continuous casting steps are also included.

[0098] The present invention adopts directional solidification and continuous melting and casting technology. The copper rod obtained by directional solidification casting has less internal grain boundaries, less impurities and bubbles, and excellent processing and use performance. The continuous melting and casting technology is to change the cold casting mold in traditional continuous casting into a heated casting mold, so as to avoid nucleation on the mold wall, completely eliminate equiaxed crystals, and make heat diffuse only along a single direction - the axial direction of the casting billet, so as to obtain a unidirectionally solidified columnar crystal continuous ingot, control the morphology of the solidification interface and the heat flow field distribution of the ingot, promote the competitive growth of axial grains, and gradually control the entire ingot by one grain, so as to realize single crystal continuous casting.

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

[0100] In an optional embodiment, the surface treatment agent includes: 3wt%-7wt% sulfuric acid, 3wt%-7wt% nitric acid, 0.03wt%-0.07wt% OP-10 agent, and the rest is pure water.

[0101] In an optional embodiment, the copper wire after rotary forging is subjected to peeling treatment and non-destructive testing steps in sequence, and the diameter of the copper wire after peeling is 1.8mm-2.2mm.

[0102] The present invention also includes a peeling step, which can remove surface defects of the 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 consistent, thereby improving the processability and laying the foundation for the stable and consistent breaking force and elongation of the bonding copper wire.

[0103] In an optional embodiment, the peeling speed is 15m / min-20m / min, and the post-tensioning force is 150N-180N.

[0104] In an optional embodiment, the method further includes performing a degreasing and polishing step on the copper wire after drawing.

[0105] In an optional embodiment, the degreasing and polishing treatment temperature is 40°C-50°C.

[0106] In an optional embodiment, the polishing agent includes: 10wt%-15wt% sodium hydroxide, 18wt%-23wt% sodium phosphate, 10wt%-15wt% sodium carbonate, 1wt%-3wt% OP-10 agent, and the rest is water.

[0107] In an optional embodiment, in step (2), the drawing speed during the continuous casting process is 50m / min-60m / min.

[0108] In a third aspect, the present invention further provides an application of the above-mentioned bonding copper wire in electronic packaging.

[0109] In the present invention, the drawing liquid in the continuous drawing and withdrawing steps has the functions of lubrication, cooling, cleaning and the like.

[0110] In the present invention, zero-slip wire drawing can realize independent control of each traction wheel without slipping, and can be arbitrarily matched with molds. Each unit is composed of a mold, a driving wheel, and a tension rod. The control system directly controls ten sets of independent driving wheels and the guide wheels before and after the mold to ensure that the wire enters / exits the mold hole directly.

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

[0112] Example 1

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

[0114] The contents of the components in the bonding copper wire are: 45 ppm phosphorus, 35 ppm silver, 10 ppm lanthanum, 10 ppm yttrium, and the balance is copper.

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

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

[0117] (3) Primary annealing: The surface treated copper rod is subjected to a primary homogenization annealing under vacuum conditions; wherein the annealing temperature is 550° C. and the annealing time is 4.5 h.

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

[0119] (5) Secondary annealing: The rolled copper rod is subjected to secondary annealing at 450°C for 2.5 h under nitrogen (purity of 99.9999%), and then subjected to two rotary forgings to a copper wire with a diameter of 2.03 mm; specifically:

[0120] (6) Stripping and nondestructive testing: The copper wire after rotary forging was stripped to a diameter of 2.00 mm, and then nondestructive testing was performed, wherein the stripping speed was 16 m / min and the post-tension was 180 N.

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

[0122] First time: drawing to a diameter of 0.38 mm, wherein the elongation is 15%-18%, the speed is 300 m / min, the concentration of the drawing liquid is 1.6 wt%, and the annealing temperature is 380°C;

[0123] Second time: drawing to a diameter of 0.1 mm, wherein the elongation is 13%-16%, the speed is 400 m / min, the concentration of the drawing liquid is 1.2 wt%, and the annealing temperature is 360°C.

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

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

[0126] First time: drawing to a diameter of 0.05716 mm; wherein the elongation is 10%-13%, the speed is 600 m / min, and the concentration of the drawing liquid is 2.2 wt%;

[0127] Second time: drawing to a diameter of 0.03559 mm; wherein the elongation is 8%-10%, the speed is 800 m / min, and the concentration of the drawing liquid is 1.8 wt%;

[0128] The third time: drawing the copper wire to a diameter of 0.01986 mm; wherein the elongation is 8%-9%, the speed is 1000 m / min, and the concentration of the drawing liquid is 1.1 wt%.

[0129] (10) After the drawing process is completed, three annealing processes are performed in a vertical annealing machine. The annealing temperature is 420° C., the annealing time is 0.35 s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, a bonding copper wire is obtained.

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

[0131] Example 2

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

[0133] The contents of various components in the bonding copper wire are: phosphorus 42ppm, silver 38ppm, lanthanum 8ppm, yttrium 8ppm, and the balance is copper.

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

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

[0136] (3) Primary annealing: The surface treated copper rod is subjected to a primary homogenization annealing under vacuum conditions; wherein the annealing temperature is 600° C. and the annealing time is 4.2 h.

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

[0138] (5) Secondary annealing: The rolled copper rod is subjected to secondary annealing at 425°C for 2 h under the protection of nitrogen (purity of 99.9999%), and then subjected to two rotary forgings to a copper wire with a diameter of 2.03 mm; specifically:

[0139] (6) Stripping and nondestructive testing: The copper wire after rotary forging was stripped to a diameter of 2.00 mm, and then nondestructive testing was performed, wherein the stripping speed was 18 m / min and the post-tension was 165 N.

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

[0141] First time: drawing to a diameter of 0.38 mm, wherein the elongation is 15%-18%, the speed is 350 m / min, the concentration of the drawing liquid is 2.0 wt%, and the annealing temperature is 350°C;

[0142] Second time: drawing to a diameter of 0.1 mm, wherein the elongation is 13%-16%, the speed is 500 m / min, the drawing liquid concentration is 1wt%, and the annealing temperature is 340°C.

[0143] (8) Degreasing and polishing: The copper wire after continuous drawing and retreating is subjected to degreasing and polishing treatment; wherein 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 by non-slip wire drawing machine: The degreased and polished copper wire is deep drawn three times to a diameter of 0.01986 mm; specifically:

[0145] First time: drawing to a diameter of 0.05716 mm; wherein the elongation is 10%-13%, the speed is 550 m / min, and the concentration of the drawing liquid is 2.5 wt%;

[0146] Second time: drawing to a diameter of 0.03559 mm; wherein the elongation is 8%-10%, the speed is 750 m / min, and the concentration of the drawing liquid is 2.0 wt%;

[0147] The third time: drawing the copper wire to a diameter of 0.01986 mm; wherein the elongation is 8%-9%, the speed is 950 m / min, and the concentration of the drawing liquid is 1.5 wt%.

[0148] (10) After the drawing process is completed, three annealing processes are performed in a vertical annealing machine. The annealing temperature is 380° C., the annealing time is 0.3 s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, a bonding copper wire is obtained.

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

[0150] Example 3

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

[0152] The contents of various components in the bonding copper wire are: phosphorus 48ppm, silver 32ppm, lanthanum 12ppm, yttrium 8ppm, and the balance is copper.

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

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

[0155] (3) Primary annealing: The surface treated copper rod is subjected to a primary homogenization annealing under vacuum conditions; wherein the annealing temperature is 500° C. and the annealing time is 5 h.

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

[0157] (5) Secondary annealing: The rolled copper rod is subjected to secondary annealing at 400°C for 3 h under the protection of nitrogen (purity of 99.9999%), and then subjected to two rotary forgings to a copper wire with a diameter of 2.03 mm; specifically:

[0158] (6) Stripping and nondestructive testing: The copper wire after rotary forging is stripped to a diameter of 2.00 mm, and then nondestructive testing is performed, wherein the stripping speed is 20 m / min and the post tension is 150 N.

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

[0160] First time: drawing to a diameter of 0.38 mm, wherein the elongation is 15%-18%, the speed is 400 m / min, the concentration of the drawing liquid is 1.8 wt%, and the annealing temperature is 400°C;

[0161] Second time: drawing to a diameter of 0.1 mm, wherein the elongation is 13%-16%, the speed is 300 m / min, the concentration of the drawing liquid is 1.5 wt%, and the annealing temperature is 390°C.

[0162] (8) Degreasing and polishing: The copper wire after continuous drawing and retreating is subjected to degreasing and polishing treatment; wherein 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 by non-slip wire drawing machine: The degreased and polished copper wire is deep drawn three times to a diameter of 0.01986 mm; specifically:

[0164] First time: drawing to a diameter of 0.05716 mm; wherein the elongation is 10%-13%, the speed is 650 m / min, and the concentration of the drawing liquid is 2.0 wt%;

[0165] Second time: drawing to a diameter of 0.03559 mm; wherein the elongation is 8%-10%, the speed is 850 m / min, and the concentration of the drawing liquid is 1.5 wt%;

[0166] The third time: drawing the copper wire to a diameter of 0.01986 mm; wherein the elongation is 8%-9%, the speed is 1050 m / min, and the concentration of the drawing liquid is 1.0 wt%.

[0167] (10) After the drawing process is completed, three annealing processes are performed in a vertical annealing machine. The annealing temperature is 450° C., the annealing time is 0.4 s, and the protective gas is 95% nitrogen + 5% hydrogen. After the annealing is completed, a bonding copper wire is obtained.

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

[0169] Comparative Example 1

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

[0171] Comparative Example 2

[0172] This comparative example provides a method for preparing a bonding copper wire, which is basically the same as the steps of Example 1, except that the continuous drawing and withdrawing steps in step (7) are replaced by a conventional drawing method, specifically comprising: 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%, no annealing heat treatment in the middle, and annealing treatment is performed when the diameter is 0.1039 mm, and the temperature is 400°C.

[0173] Comparative Example 3

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

[0175] Comparative Example 4

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

[0177] Comparative Example 5

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

[0179] Comparative Example 6

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

[0181] Experimental Example 1

[0182] The first continuous drawing and withdrawing experiment was carried out on Example 1 after the peeling treatment and the comparative example 1 without the peeling treatment, and the number of wire breaks was recorded. That is, the copper wire with a diameter of 2.00 mm was directly drawn to a diameter of 0.38 mm, and the wire was fixedly drawn for 5000 m. The number of wire breaks in this process was recorded. The results are shown in the following table.

[0183] Table 1 Number of wire breaks during the first continuous drawing and retraction process of Example 1 and Comparative Example 1

[0184] Example 1 Comparative Example 1 Sample 1 0 10 Sample 2 0 8 Sample 3 1 11

[0185] It can be seen from the above table that comparative example 1 has a large number of wire breakages during the first continuous drawing and withdrawing process, while example 1 of the present invention has significantly improved processability of the copper wire after continuous rolling-rotary forging-stripping steps, which can effectively reduce the number of wire breakages.

[0186] At the same time, compared with the traditional bonding copper wire drawing process, calendering and rotary forging can significantly improve the production efficiency. It takes about 6 hours to pull an 8mm copper cast rod to 2.03mm using the traditional mold drawing process, but it only takes about 1 hour to calender and rotary forge to 2.03mm. At the same time, the use of calendering and rotary forging does not involve the use of molds, which can save costs for the company.

[0187] Experimental Example 2

[0188] According to GB / T10573-2020 "Non-ferrous metal wire tensile test method", use IMS-W101 (INSTRON1kN ) The tensile tester was used to test the breaking force and elongation of the bonding copper wires prepared in the above Example 1 and Comparative Example 2. The results are shown in the following table.

[0189] Table 2 Bonding copper wire performance test results of Example 1 and Comparative Example 2

[0190]

[0191] It can be seen from the above table that the bonding copper wire of the present invention adopts a continuous pulling and continuous withdrawing method, and the mechanical properties are more stable and the consistency is higher, which lays a good foundation for improving the overall quality of the product. At the same time, Example 1 can realize a continuous production process through the continuous pulling and continuous withdrawing method, reduce the waiting time and process change time in the production process, improve production efficiency, ensure constant temperature and speed throughout the production process, and ensure the stability and consistency of product quality.

[0192] Experimental Example 3

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

[0194] (1) Breaking force and elongation test: refer to GB / T10573-2020 "Non-ferrous metal filament tensile test method";

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

[0196] (3) Using a scanning electron microscope to observe the surface morphology and microstructure of the cross section of the cast rod, a self-developed pore analysis method was developed with a full score of 36 points. The scoring parameters include pore size and number, etc. The higher the value, the smaller the pore volume ratio, which means the higher the density of the ingot;

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

[0198] (5) Resistivity test: According to GB / T3048.4-2007 "Electrical performance test methods for wires and cables Part 4: Conductor DC resistance test".

[0199] Table 3 Performance test results of bonding copper wires prepared in various embodiments and comparative examples

[0200]

[0201] As can be seen from the above table, the bonding copper wires prepared in Examples 1 to 3 of the present invention have a longer elongation, a higher breaking force, a longer uniaxial drawing length, a higher cast rod porosity score, and better reliability and resistivity. At the same time, the addition of trace elements silver, lanthanum and yttrium in the present invention has played a good role in improving the mechanical properties and reliability of the bonding copper wire, making it have a wide range of application prospects in the fields of microelectronic packaging and semiconductor manufacturing. Compared with Comparative Example 1, the embodiment adds calendering and rotary forging deformation processes, which can effectively improve the mechanical properties of the bonding copper wire; after continuous calendering, the thickness of the metal material can be significantly reduced, achieving the effect of reducing its own weight, improving strength, and being able to withstand larger loads and pressures; rotary forging is a multiple deformation process with low energy, which can reduce the pores inside the material while improving strength. Compared with Comparative Example 2, the application of continuous drawing and annealing process can effectively improve the consistency between product batches, and the metal is annealed immediately after drawing, which can better eliminate or reduce tissue defects and residual stress, refine tissue grains, and restore plasticity, thereby improving product mechanical properties and reliability; compared with Comparative Example 3, the application of non-slip wire drawing technology can significantly reduce the incidence of sliding during the wire drawing process, ensure the stability and consistency of the wire drawing operation, prevent stress concentration and uneven deformation caused by sliding, and further promote the homogenization and densification of the internal structure of the bonding wire. When subjected to tensile force, the stress can be more evenly distributed, significantly enhancing its resistance to breakage; in addition, the non-slip wire drawing technology also enhances the uniform deformation ability of the bonding wire during the stretching process by avoiding local deformation and damage caused by sliding, so that the bonding wire can withstand greater deformation during the stretching process without breaking easily, thereby significantly improving its elongation. Figure 2This is a surface quality comparison diagram of Example 1 of the present invention and Comparative Example 3 (magnification is 3000 times). It can be seen that after Example 1 uses a non-slip drawing process, the surface quality of the wire can be greatly improved, there are no scratches, and the surface is smoother. In Comparative Example 4, no silver element is added, resulting in a significant decrease in the reliability of the bonding copper wire. This is because the addition of silver elements can improve the heat dissipation performance of the copper wire, so that it can dissipate heat more effectively in a high temperature environment and maintain stable performance; in Comparative Example 5, no lanthanum element is added, and all the properties of the bonding copper wire are reduced. This is because lanthanum elements can inhibit the nucleation and growth of recrystallization, and can cooperate with phosphorus elements to promote the refinement of grain structure and enhance the mechanical properties of the finished bonding copper wire; in Comparative Example 6, no yttrium element is added, and the resistivity of the bonding copper wire is significantly increased, which hinders the transmission of electrical signals. This is because the addition of Y elements can refine the copper grains, effectively reduce impurities in copper, weaken lattice distortion, reduce the probability of electron scattering, and further improve the conductive performance.

[0202] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A bonding copper wire, It is characterized in that The chemical composition of the bonding copper wire includes, by weight percentage: 42ppm-48ppm phosphorus, 32ppm-38ppm silver, 8ppm-12ppm lanthanum, 8ppm-12ppm yttrium, and the balance copper; The breaking force of the bonding copper wire is ≥7.5 cN, the elongation is 11.0%-15.0%, and the reliability is ≥300 cycles.

2. The bonding copper wire according to claim 1, It is characterized in that The chemical composition of the bonding copper wire includes: 44ppm-46ppm phosphorus, 34ppm-36ppm silver, 9ppm-11ppm lanthanum, 9ppm-11ppm yttrium, and the balance copper; The breaking force of the bonding copper wire is ≥7.6 cN, and the elongation is 11.5%-12%.

3. The bonding copper wire according to claim 1 or 2, It is characterized in that 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; The breaking force of the bonding copper wire is 7.9 cN, and the elongation is 11.6%.

4. A method for preparing the bonding copper wire according to any one of claims 1 to 3, It is characterized in that The steps include: (1) mixing phosphorus, silver, lanthanum and yttrium with a portion of high-purity copper respectively and then smelting them once to obtain a phosphorus-copper master alloy, a silver-copper master alloy and a lanthanum-yttrium-copper master alloy; (2) mixing the phosphorus-copper master alloy, the silver-copper master alloy, the lanthanum-yttrium-copper master alloy and the remaining high-purity copper and then performing secondary smelting to obtain a copper rod with a diameter of 8 mm to 10 mm; (3) subjecting the copper rod to an annealing treatment, and then continuously rolling the copper rod to a diameter of 4.2 mm to 4.4 mm; (4) performing secondary annealing on the rolled copper rod, and then performing rotary forging to obtain a copper wire with a diameter of 2.0 mm to 2.1 mm; (5) performing continuous drawing and continuous withdrawal wire drawing and zero-slip wire drawing on the rotary forged copper wire to obtain a copper wire with a diameter of 0.018 mm to 0.030 mm; (6) The copper wire is subjected to three annealing treatments to obtain the bonding copper wire.

5. The method for preparing the bonding copper wire according to claim 4, It is characterized in that In the continuous calendering step, the elongation is 18%-20%; And / or, the number of rotary forgings includes at least 2 times; the first rotary forging is rotary forging to a diameter of 2.9 mm-3.1 mm, and the second rotary forging is rotary forging to a diameter of 2.0 mm-2.1 mm.

6. The method for preparing the bonding copper wire according to claim 4, It is characterized in that The primary annealing temperature is 500°C-600°C, the primary annealing time is 4h-5h; the annealing period is vacuum condition; And / or, the secondary annealing temperature is 400°C-500°C, the secondary annealing time is 2h-3h; the annealing atmosphere is an inert atmosphere; And / or, the temperature of the third annealing is 380° C.-450° C., the time of the second annealing is 0.3 s-0.4 s; and the annealing atmosphere is nitrogen and hydrogen atmosphere.

7. The method for preparing the bonding copper wire according to claim 4, It is characterized in that In the phosphorus-copper master alloy, the phosphorus content 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 content of lanthanum is 0.75wt%-1.5wt%, and the content of yttrium is 0.6wt%-0.8wt%; And / or, the primary smelting temperature is 1000°C-1600°C, and the time is 4h-6h; And / or, the secondary smelting is carried out at a temperature of 1200° C.-1250° C. and for a time of 8 h-10 h.

8. The method for preparing the bonding copper wire according to claim 4, It is characterized in that The continuous pulling and retracting steps include at least two times; In the first continuous drawing and annealing, the wire is continuously drawn and annealed to a diameter of 0.3 mm to 0.4 mm, an elongation of 15% to 18%, a speed of 300 m / min to 400 m / min, a concentration of the drawing liquid of 1.5 wt% to 2.0 wt%, and an annealing temperature of 350° C. to 400° C.; In the second continuous drawing and annealing, the wire is continuously drawn and annealed 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 wire drawing liquid concentration of 1.0 wt% to 1.5 wt%, and an annealing temperature of 340° C. to 390° C.; And / or, the step of seamless wire drawing includes at least three times; In the first differential slip wire drawing, the wire is drawn to a diameter of 0.05 mm to 0.06 mm, an elongation of 10% to 13%, a speed of 550 m / min to 650 m / min, and a wire drawing liquid concentration of 2.0 wt% to 2.5 wt%; In the second differential slip wire drawing, the wire is drawn to a diameter of 0.03 mm to 0.04 mm, an elongation of 8% to 10%, a speed of 750 m / min to 850 m / min, and a wire drawing liquid concentration of 1.5 wt% to 2.0 wt%; In the third differential slip wire drawing, the wire is drawn to a diameter of 0.01 mm-0.02 mm, an elongation of 8%-9%, a speed of 950 m / min-1050 m / min, and a drawing liquid concentration of 1.0 wt%-1.5 wt%.

9. The method for preparing the bonding copper wire according to claim 4, It is characterized in that After the secondary smelting, it also includes directional solidification and continuous casting steps; And / or, it also includes the steps 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 rest is pure water; And / or, the copper wire after rotary forging is subjected to peeling treatment and non-destructive testing in sequence, and the diameter of the copper wire after peeling is 1.8mm-2.2mm; The peeling speed is 15m / min-20m / min, and the post tension is 150N-180N; And / or, it also includes the step of degreasing and polishing the copper wire after drawing; The degreasing and polishing treatment temperature is 40°C-50°C; 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 rest is water; And / or, in step (2), the drawing speed during the continuous casting process is 50m / min-60m / min.

10. Use of the bonding copper wire according to any one of claims 1 to 3, or the bonding copper wire prepared by the preparation method according to any one of claims 4 to 9 in electronic packaging.

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