A high gold bond alloy wire, its production process and application

Abstract

This invention relates to the field of semiconductor packaging materials, specifically to a high-gold-bond alloy wire, its production process, and its applications. The process includes the following steps: melting and rapidly solidifying raw materials with a purity ≥99.999% to prepare a gold alloy ingot with a gold content ≥99.99%; hot-working and multi-pass cold drawing of the gold alloy ingot, with intermediate annealing during cold drawing to obtain an intermediate wire with a diameter between 50μm and 200μm; applying plastic torsional deformation to the intermediate wire at a degree of 30 turns / meter to 120 turns / meter; subjecting the torsional-deformed intermediate wire to rapid heat treatment at a temperature of 350℃ to 550℃ for 2s to 8s, followed by rapid cooling; and precision drawing the heat-treated wire to a final product with a diameter of 15μm to 33μm. This invention, through the coordination of components and processes, solves the problem of slippage or poor soldering defects, achieving the goal of producing high-strength, low-curvature products.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor packaging materials, in particular to a high gold bonding wire and its production process and application. BACKGROUND

[0002] In the field of semiconductor packaging, bonding wires are used as conductive wires to connect the chip pads with external pins. The performance of the bonding wires is crucial and directly affects the reliability of the circuit, the quality of signal transmission and the yield of the final product. With the development of integrated circuits towards high density, high frequency and high power, the comprehensive performance of the bonding wires is required to be almost contradictory: on the one hand, in order to adapt to more complex wiring layout and thinner overall packaging, the gold wire is required to have higher strength and rigidity to ensure stable wire arc with low arc and anti-collapse; on the other hand, in order to ensure signal integrity and reduce power consumption, the gold wire is required to have as low resistivity as possible, which fundamentally requires maintaining extremely high gold purity.

[0003] The prior art mainly follows two technical paths to improve the strength of the gold wire, but both have significant defects. The first path is to use a large proportion of alloying, such as adding a few tenths of beryllium or a few percent of palladium, platinum and other elements in gold. Although this method can effectively improve the strength, it seriously sacrifices the conductivity, resulting in a significant increase in resistivity, which cannot meet the needs of high-frequency and high-current devices. More importantly, such high-strength alloy wires have a hardness that is too high to allow the ultrasonic energy to effectively break the dense oxide layer on the surface of the chip aluminum pad during bonding, which can cause slip ball or false welding defects, seriously affecting the bonding yield and long-term reliability. In addition, the biological toxicity of beryllium also poses a production safety and environmental hazard.

[0004] The second path is to maintain high purity and strengthen through conventional cold working and heat treatment processes. However, the inherent strength of pure gold or high-purity gold wire is low, and the wire arc prepared therefrom is easily deformed and collapsed by external forces in subsequent processes, which cannot meet the low-arc packaging requirements. At the same time, the lack of strength also makes the gold wire easily deformed under the bonding pressure, which is also not conducive to the formation of stable and reliable solder joints. Therefore, the field has long been faced with a key technical bottleneck: how to simultaneously achieve mechanical properties comparable to medium and high-strength alloys while maintaining the total gold content of the gold wire at not less than 99.99% to ensure its excellent conductivity, and at the same time, have excellent bonding reliability.

[0005] CN106298721A discloses a bonding wire and its preparation method. The bonding wire has the following composition (by mass percentage): gold ≥ 99.99%, silver 0.0010-0.0020%, iron 0.0001-0.0010%, lead 0.0005-0.0015%, magnesium 0.0001-0.0010%, copper 0.00010-0.0020%, silicon 0-0.0010%, and rare earth elements 0.0003-0.0008%. The preparation method mainly includes primary refining, secondary refining, continuous casting, wire drawing, cleaning, annealing, winding, and packaging. Based on the optimized composition, rare earth elements are further added. At the same time, combined with the optimization of process parameters, the strength of the ultrafine bonding wire, such as elongation and breaking load, is improved, the length of the heat-affected zone is significantly shortened, the curvature is effectively reduced, the service life of the bonding wire is improved, and the application range of the bonding wire is broadened. However, it did not solve the aforementioned problems of slip ball or poor soldering, nor did it achieve the goal of producing high-strength, low-curvature products. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a high-gold-bonded alloy wire, its manufacturing process, and its applications. By coordinating the composition and process, the problem of slip ball or incomplete soldering defects is solved, achieving the goal of producing high-strength, low-curvature products.

[0007] A manufacturing process for high gold bond alloy wire includes the following steps:

[0008] Raw materials with a purity of ≥99.999% are smelted and rapidly solidified to produce gold alloy ingots with a gold content of ≥99.99%.

[0009] The gold alloy ingot is subjected to hot working and multiple cold drawing processes, with intermediate annealing during the cold drawing process, to obtain intermediate wire with a diameter between 50μm and 200μm.

[0010] Plastic torsional deformation is applied to the intermediate filament, and the degree of torsional deformation is 30 turns / meter to 120 turns / meter;

[0011] The intermediate filament, after being twisted and deformed, is subjected to rapid heat treatment at a temperature of 350℃-550℃ for 2s-8s, followed by rapid cooling.

[0012] The heat-treated wire is precisely drawn to a final product with a diameter of 15μm-33μm.

[0013] This invention is based on the melting and rapid solidification of raw materials with a purity of not less than 99.99%. This step aims to obtain an ingot with highly uniform composition and refined initial grains. Insufficient cooling rate will lead to coarse grains, creating potential problems for subsequent plastic processing. Subsequent hot working and multi-pass cold drawing aim to gradually refine the grains and introduce dislocations. Intermediate annealing during this process is crucial, aiming to achieve a balance between work hardening and ductility recovery, preventing the material from cracking during subsequent torsion due to excessive defect accumulation. The core of this invention lies in applying plastic torsion deformation of intermediate wires with a diameter of 50μm-200μm at 30 turns / meter to 120 turns / meter. This process is not simple work hardening, but rather induces high-density dislocation walls and strong shear texture within the material through intense shear strain, providing the necessary deformation energy storage and crystallographic orientation conditions for the formation of nanotwins during subsequent recrystallization. If the degree of torsion is below this range, the deformation energy storage is insufficient, making it difficult to effectively stimulate the formation of nanostructures; if it exceeds this range, it may lead to excessive lattice damage, microcrack initiation, or even direct breakage of the filament. Within the subsequent rapid heat treatment window (350℃-550℃, 2s-8s), the material undergoes dynamic recovery and rapid recrystallization. On the one hand, rapid heating inhibits the long-term relaxation of dislocations and the formation of coarse precipitates; on the other hand, precisely controlled temperature and time provide optimal kinetic conditions for recrystallization nucleation based on high-density deformation energy storage. During this process, the shear bands and dislocation cell walls introduced by the initial torsion become the preferred nucleation sites for nanoscale twins and ultrafine equiaxed grains, ultimately forming a "double-interface" reinforced structure where nanotwin boundaries strengthen the intragranular region and fine grain boundaries strengthen the grain boundaries. The purpose of rapid cooling after heat treatment is to fix this metastable reinforced microstructure and prevent grain growth or coarsening due to slow cooling. The final precision drawing to the target diameter involves accurately calibrating the wire dimensions based on the already obtained reinforced microstructure, and may introduce additional dislocation reinforcement. However, the amount of deformation must be strictly controlled to avoid damaging the already formed favorable nanostructure.

[0014] In terms of component compatibility, microalloying elements (such as palladium and cerium) in the raw materials, with a total content not exceeding 0.01%, act as microstructure stabilizers and grain boundary purifiers. For example, palladium, through solid solution dragging, can effectively pin grain boundary migration and inhibit excessive grain growth during recrystallization and subsequent thermal effects; while rare earth elements such as cerium can preferentially segregate at grain boundaries, purifying the interface and improving interfacial bonding strength and thermal stability. The content of these elements is strictly limited to maximize the strengthening effect through their interfacial effect while minimizing their negative impact on conductivity. If their content exceeds the range, it will not only unnecessarily increase resistivity but may also form brittle intermetallic compounds, deteriorating processability and bonding performance.

[0015] Preferably, the raw material contains ≤0.01% of microalloying elements, wherein the microalloying elements are one or more of palladium, cerium, and calcium.

[0016] Preferably, the microalloying elements include palladium at a mass percentage of 0.001%-0.008% and cerium at a mass percentage of 0.0005%-0.002%.

[0017] Palladium's primary function is to improve the overall strength and recrystallization temperature of materials through solid solution strengthening. When its content is below 0.001%, the strengthening effect is insufficient; while exceeding 0.008% will significantly negatively impact conductivity and increase costs. Cerium's main role is to refine grains and purify grain boundaries. It effectively inhibits grain growth and improves the material's toughness. Its effect is not significant below 0.0005%, and exceeding 0.002% may form brittle compounds, thus impairing the material's mechanical properties. This composition range is compatible with rapid heat treatment processes of 350℃-550℃, enabling products to possess both high strength and high reliability through the synergistic effect of grain refinement and solid solution strengthening, while ensuring high conductivity.

[0018] Preferably, the rapid solidification involves controlling the cooling rate of the alloy melt to be ≥100℃ / s, thereby obtaining a microcrystalline structure with a grain size <50μm.

[0019] By significantly increasing the undercooling of the alloy melt through extremely high cooling rates, the nucleation rate is greatly enhanced and grain growth is suppressed, ultimately resulting in microcrystalline ingots with grain sizes less than 50 micrometers. Insufficient cooling rates will lead to coarse as-cast grains, which will not only deteriorate the subsequent hot working and cold drawing processes but also embed microscopic defects within the material, severely limiting the strength and reliability limits of the final product. This step provides a high-quality raw material foundation with uniform composition and refined microstructure for all subsequent fine-grained structural control, and is an indispensable prerequisite for the entire process.

[0020] Preferably, the intermediate annealing is a rapid electro-annealing, and the current density of the rapid electro-annealing is 200 A / mm². 2 Up to 400 A / mm², with a power-on time of 2s-5s.

[0021] Preferably, the degree of plastic torsional deformation is 50 turns / meter to 100 turns / meter.

[0022] Preferably, the rapid heat treatment is carried out in a temperature range of 450℃-500℃ to obtain a uniform recrystallized structure with an average grain size of less than 5μm.

[0023] Intermediate annealing uses a current density of 200 A / mm 2Rapid annealing with current up to 400 A / mm² and an energizing time of 2-5 s is designed to achieve efficient and localized dislocation recombination. The mechanism utilizes the Joule heating effect to bring the wire to its recrystallization temperature in a very short time, effectively eliminating work hardening accumulated during cold drawing, restoring material ductility, and preparing for subsequent intense plastic torsion. If the current density or time is insufficient, dislocation elimination will be incomplete, resulting in insufficient ductility and easy breakage during torsion; if the parameters are too high, it may lead to abnormal grain growth or localized melting, disrupting the uniformity of the microstructure.

[0024] The optimal degree of plastic torsional deformation is 50 turns / meter to 100 turns / meter, based on a balance between deformation energy storage and the controllability of microscopic defects. Torsion within this range introduces high-density dislocations and intense shear strain, providing sufficient nucleation driving force for the formation of nanotwins and ultrafine recrystallized grains during subsequent heat treatment. Insufficient torsion results in limited deformation energy storage, making it difficult to induce sufficient recrystallization and nanostructure formation; excessive torsion, on the other hand, causes the defect density to exceed a critical value, leading to microcrack initiation and ultimately impairing the material's integrity and final mechanical properties.

[0025] Optimizing the rapid heat treatment temperature within a narrow range of 450°C to 500°C is key to achieving directional control of the microstructure. Within this optimal temperature window, the high-defect regions introduced by the initial torsion process can undergo sufficient and rapid recovery and recrystallization, forming a uniform recrystallized structure with an average grain size of less than 5 micrometers. This temperature is highly synergistic with the aforementioned rapid electro-annealing and specific torsion parameters: it ensures that the energy stored by torsion can be effectively used to drive recrystallization, while avoiding rapid grain coarsening caused by excessively high temperatures. If the temperature is too low, the recrystallization process is slow or incomplete, and the strength potential cannot be fully released; if the temperature is too high, the grains grow rapidly, and the material's strength and creep resistance will significantly decrease.

[0026] Preferably, the rapid heat treatment or the rapid electro-annealing is carried out in an inert gas protective atmosphere with a purity of ≥99.999%.

[0027] Preferably, the rapid cooling rate after the rapid heat treatment is ≥100℃ / s.

[0028] This invention also proposes a high gold bond alloy wire produced by the above-mentioned high gold bond alloy wire production process, wherein the total gold content of the high gold bond alloy wire is ≥99.99%, its diameter is 15μm-33μm, and it simultaneously meets the following performance indicators:

[0029] The elongation rate is 5%-9%;

[0030] Resistivity ≤ 2.5 × 10 -8 Ω·m;

[0031] Bond strength ≥ 5 cN.

[0032] The high gold bond alloy wire proposed in this invention is applied to semiconductor packaging.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. In terms of composition design, this invention strictly limits the total gold content to no less than 99.99% and introduces microalloying elements such as palladium and cerium in total of no more than 0.01%. While maximizing the preservation of the excellent conductivity of high-purity gold, it effectively utilizes solid solution strengthening and grain boundary purification mechanisms. This composition system successfully overcomes the defects of the prior art, which suffers from a significant increase in resistivity and a decrease in bonding interface reliability due to the use of large-proportion alloying, achieving a synergy between high strength and low resistivity.

[0035] 2. From a process perspective, this invention introduces high-density shear strain through torsional deformation within a specific range, and combines this with rapid heat treatment to achieve microstructure control within a narrow temperature range, successfully forming a strengthened microstructure characterized by nanotwins and ultrafine grains in a high-purity gold matrix. This process not only solves the problem of poor arc stability caused by the low inherent strength of high-purity gold wire in the prior art, but also effectively avoids bonding slippage and incomplete soldering defects common in high-strength alloy wires by improving the material's plastic deformation capability, thus simultaneously achieving the comprehensive goals of high strength, low arc, and high bonding reliability. Detailed Implementation

[0036] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] General Implementation Examples

[0038] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0039] Raw materials with a purity of ≥99.999% are smelted and rapidly solidified to produce gold alloy ingots with a gold content of ≥99.99%.

[0040] The gold alloy ingot is hot-worked by heating it to 600-750℃ and holding it for 10-30 minutes. Then, it is plastically processed by hot rolling or hot extrusion, with the cumulative deformation controlled within the range of 40%-70%. Then, it is cold-drawn in 3 passes, with intermediate annealing during the cold drawing process, to obtain intermediate wire with a diameter between 50μm and 200μm.

[0041] Plastic torsional deformation is applied to the intermediate filament, and the degree of torsional deformation is 30 turns / meter to 120 turns / meter;

[0042] The intermediate filament, after being twisted and deformed, is subjected to rapid heat treatment at a temperature of 350℃-550℃ for 2s-8s, followed by rapid cooling.

[0043] The heat-treated wire is precisely drawn to a final product with a diameter of 15μm-33μm.

[0044] In some preferred embodiments, the raw material contains ≤0.01% of a microalloying element, wherein the microalloying element is one or more of palladium, cerium, and calcium.

[0045] In some preferred embodiments, the microalloying elements include palladium at a mass percentage of 0.001%-0.008% and cerium at a mass percentage of 0.0005%-0.002%.

[0046] In some preferred embodiments, the rapid solidification is achieved by controlling the cooling rate of the alloy melt to be ≥100℃ / s, thereby obtaining a microcrystalline structure with a grain size <50μm.

[0047] In some preferred embodiments, the intermediate annealing is rapid power-on annealing, wherein the current density of the rapid power-on annealing is 200 A / mm²-400 A / mm², and the power-on time is 2s-5s.

[0048] In some preferred embodiments, the degree of plastic torsional deformation is 50 turns / meter to 100 turns / meter.

[0049] In some preferred embodiments, the rapid heat treatment is performed in a temperature range of 450°C to 500°C to obtain a uniform recrystallized structure with an average grain size of less than 5 μm.

[0050] In some preferred embodiments, the rapid heat treatment or the rapid electro-annealing is performed in an inert gas protective atmosphere with a purity of ≥99.999%.

[0051] In some preferred embodiments, the rapid cooling rate after the rapid heat treatment is ≥100℃ / s.

[0052] Example 1

[0053] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0054] 0.005% of microalloying elements (0.004% by mass of palladium and 0.001% by mass of cerium) were added to gold with a purity of 99.999%. The mixture was smelted and then rapidly solidified at a cooling rate of 100℃ / s under a protective atmosphere of 99.999% argon gas to produce a gold alloy ingot with a gold content of 99.994% and a grain size of 45μm.

[0055] The gold alloy ingot was hot-worked by heating it to 675℃ and holding it for 20 minutes. Then, it was plastically processed by hot rolling, with the cumulative deformation controlled within 55%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under a protective atmosphere of 99.999% argon gas, with a current density of 300 A / mm² and an energizing time of 3.5s, to obtain an intermediate wire with a diameter of 125μm.

[0056] Plastic torsional deformation is applied to the intermediate filament, with a torsional deformation degree of 75 turns / meter;

[0057] Under a protective atmosphere of 99.999% argon gas, the intermediate filament that has undergone torsion deformation was subjected to rapid heat treatment at a temperature of 450℃ for 5s, resulting in an average grain size of 4μm. Subsequently, it was rapidly cooled at a cooling rate of 100℃ / s.

[0058] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0059] Example 2

[0060] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0061] 0.0028% of microalloying elements (palladium at 0.002% by mass and cerium at 0.0008% by mass) were added to gold with a purity of 99.999%. The mixture was smelted and then rapidly solidified at a cooling rate of 150℃ / s under a protective atmosphere of 99.999% argon gas to prepare a gold alloy ingot with a gold content of 99.996% and a grain size of 40μm.

[0062] The gold alloy ingot was hot-worked by heating it to 600℃ and holding it for 30 minutes. Then, it was plastically processed by hot extrusion, with the cumulative deformation controlled within 40%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under the protection of 99.999% argon gas, with a current density of 200 A / mm² and an energizing time of 5s, to obtain an intermediate wire with a diameter of 200μm.

[0063] Plastic torsional deformation is applied to the intermediate filament, with a torsional deformation degree of 30 turns / meter;

[0064] Under a protective atmosphere of 99.999% argon gas, the intermediate filament that has undergone torsion deformation was subjected to rapid heat treatment at 350℃ for 8s, resulting in an average grain size of 4.5μm. Subsequently, it was rapidly cooled at a cooling rate of 150℃ / s.

[0065] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0066] Example 3

[0067] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0068] 0.009% of microalloying elements were added to gold with a purity of 99.999%. The microalloying elements were palladium (0.0062% by mass), cerium (0.0018% by mass), and calcium (0.001% by mass). The mixture was smelted and then rapidly solidified at a cooling rate of 200℃ / s under a protective atmosphere of 99.999% argon gas to prepare a gold alloy ingot with a gold content of 99.99% and a grain size of 35μm.

[0069] The gold alloy ingot was hot-worked by heating it to 750℃ and holding it for 10 minutes. Then, it was plastically processed by hot rolling, with the cumulative deformation controlled within 70%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under the protection of 99.999% argon gas, with a current density of 400 A / mm² and an energizing time of 2s, to obtain an intermediate wire with a diameter of 50μm.

[0070] Plastic torsional deformation is applied to the intermediate filament, with a torsional deformation degree of 120 turns / meter;

[0071] Under a protective atmosphere of 99.999% argon gas, the intermediate filament that has undergone torsion deformation was subjected to rapid heat treatment at a temperature of 550℃ for 2s, resulting in an average grain size of 3.5μm. Subsequently, it was rapidly cooled at a cooling rate of 200℃ / s.

[0072] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0073] Comparative Example 1

[0074] The only difference from Example 1 is that the current density is too low, specifically:

[0075] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0076] 0.005% of microalloying elements (0.004% by mass of palladium and 0.001% by mass of cerium) were added to gold with a purity of 99.999%. The mixture was smelted and then rapidly solidified at a cooling rate of 100℃ / s under a protective atmosphere of 99.999% argon gas to produce a gold alloy ingot with a gold content of 99.994% and a grain size of 45μm.

[0077] The gold alloy ingot was hot-worked by heating it to 675℃ and holding it for 20 minutes. Then, it was plastically processed by hot rolling, with the cumulative deformation controlled within 55%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under the protection of 99.999% argon gas, with a current density of 150 A / mm² and an energizing time of 3.5s, to obtain an intermediate wire with a diameter of 125μm.

[0078] Plastic torsional deformation is applied to the intermediate filament, with a torsional deformation degree of 75 turns / meter;

[0079] Under a protective atmosphere of 99.999% argon gas, the intermediate filament that has undergone torsion deformation was subjected to rapid heat treatment at a temperature of 450℃ for 5s, resulting in an average grain size of 4μm. Subsequently, it was rapidly cooled at a cooling rate of 100℃ / s.

[0080] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0081] Comparative Example 2

[0082] The only difference from Example 1 is that no torsional deformation operation was performed:

[0083] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0084] 0.005% of microalloying elements (0.004% palladium and 0.001% cerium by mass) were added to gold with a purity of 99.999%. The mixture was smelted and then rapidly solidified at a cooling rate of 100℃ / s under a protective atmosphere of 99.999% argon gas to produce a gold alloy ingot with a gold content of 99.994% and a grain size of 45μm.

[0085] The gold alloy ingot was hot-worked by heating it to 675℃ and holding it for 20 minutes. Then, it was plastically processed by hot rolling, with the cumulative deformation controlled within 55%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under a protective atmosphere of 99.999% argon gas, with a current density of 300 A / mm² and an energizing time of 2.5s, to obtain an intermediate wire with a diameter of 125μm.

[0086] Under a protective atmosphere of 99.999% argon gas, the intermediate filament was subjected to rapid heat treatment at 450℃ for 5s, resulting in an average grain size of 4μm. Subsequently, it was rapidly cooled at a cooling rate of 100℃ / s.

[0087] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0088] Comparative Example 3

[0089] The difference from Example 1 is that the torsional deformation is too large:

[0090] A manufacturing process for high gold bond alloy wire, comprising the following steps:

[0091] 0.005% of microalloying elements (0.004% palladium and 0.001% cerium by mass) were added to gold with a purity of 99.999%. The mixture was smelted and then rapidly solidified at a cooling rate of 100℃ / s under a protective atmosphere of 99.999% argon gas to produce a gold alloy ingot with a gold content of 99.994% and a grain size of 45μm.

[0092] The gold alloy ingot was hot-worked by heating it to 675℃ and holding it for 20 minutes. Then, it was plastically processed by hot rolling, with the cumulative deformation controlled within 55%. After that, it was cold-drawn in three passes. During the cold drawing, it was rapidly annealed under a protective atmosphere of 99.999% argon gas, with a current density of 300 A / mm² and an energizing time of 3.5s, to obtain an intermediate wire with a diameter of 125μm.

[0093] Plastic torsional deformation is applied to the intermediate filament, with a torsional deformation degree of 130 turns / meter;

[0094] Under a protective atmosphere of 99.999% argon gas, the intermediate filament that has undergone torsion deformation was subjected to rapid heat treatment at a temperature of 450℃ for 5s, resulting in an average grain size of 4μm. Subsequently, it was rapidly cooled at a cooling rate of 100℃ / s.

[0095] The heat-treated filaments are precisely drawn to a final product with a diameter of 18μm.

[0096] Performance testing:

[0097] Basic technical requirements: Refer to GB / T 8750-2014 "Bond Wires for Semiconductor Packaging", and all individual tests must meet the following requirements:

[0098] Purity (gold) ≥ 99.99%;

[0099] The elongation rate is 2%-9%;

[0100] resistivity 2×10 -8 Ω·m⁻³×10 -8 Ω·m;

[0101] Bond strength ≥ 5 cN

[0102] 18μm in diameter;

[0103] Welding effect inspection:

[0104] Chip aluminum pads of the same specifications (purity 99.99%, thickness 1μm) were selected, and 100-point batch bonding of the bonding wires of each embodiment and comparative example was carried out using a fully automatic gold wire ball bonding equipment under the same ultrasonic power (60mW), bonding pressure (80cN), and bonding temperature (180℃) parameters.

[0105] The cross-section of the bonding points was observed using a metallographic microscope (500x magnification), and the slipper ratio (the proportion of bonding points whose center offset from the center of the pad is >2μm) and the poor solder joint ratio (the proportion of bonding interfaces with gaps or bonding areas <80%) were statistically analyzed.

[0106] The ultrasonic energy feedback value during the bonding process of each sample is recorded synchronously. If the fluctuation range of the feedback value is >15%, it is judged as poor bonding stability, which indirectly reflects the risk of interface bonding defects.

[0107] The test results are shown in Table 1.

[0108] Table 1. Basic technical requirements for the performance of the embodiments and comparative examples.

[0109]

[0110] Table 2. Results of Sliding Ball / Cold Solder Defect Detection in Examples and Comparative Examples

[0111]

[0112] In the field of semiconductor packaging, bonding wires need to simultaneously meet the requirements of high gold purity to ensure low resistivity, high strength to maintain stable arc and avoid collapse, and good bonding reliability to reduce slip ball and cold solder joint defects. However, in the existing technology, although high-proportion alloying can improve strength, it significantly reduces conductivity and is prone to bonding interface problems. On the other hand, pure gold or high-purity gold wires are not strong enough by conventional processes, making it difficult to balance the overall performance, which has become a technical bottleneck in the industry. This invention overcomes this bottleneck through the synergistic design of components and processes. In terms of composition, gold with a purity ≥99.999% is used as the matrix, and microalloying elements such as palladium and cerium are introduced in a total amount ≤0.01%. Palladium can enhance material strength and recrystallization temperature through solid solution strengthening, while cerium can refine grains and purify grain boundaries. The low content of both maximizes the strengthening effect while minimizing the impact on conductivity. In terms of process, a grain-refined ingot is first obtained through rapid solidification at a cooling rate ≥100℃ / s, laying a high-quality microstructure foundation for subsequent processing. Then, it undergoes hot working, multi-pass cold drawing, and rapid electro-annealing at a current density of 200-400 A / mm². This eliminates work hardening and restores ductility while preventing abnormal grain growth. The core of this process lies in applying 30-120 turns / meter of plastic torsional deformation to the intermediate wire, introducing high-density dislocations and shear strain to accumulate sufficient deformation energy. Subsequently, it is subjected to annealing at 350-550℃ for 2-8 seconds. Rapid heat treatment causes the defect region introduced by torsion to form nanotwins and an ultrafine recrystallized structure with an average grain size of less than 5μm. Combined with rapid cooling at ≥100℃ / s to fix the reinforced structure, the target diameter product is finally obtained by precision drawing. This design retains the low resistivity brought by high gold purity, achieves high strength by means of "dual interface" reinforced structure, improves the plastic deformation capacity of the material, and enhances the bonding reliability.

[0113] Compared with the examples, Comparative Example 1 suffered from insufficient annealing due to the low intermediate annealing current density. The dislocations accumulated during the early cold drawing were not effectively eliminated, resulting in insufficient ductility of the wire. This made it prone to micro-defects during subsequent processing, which in turn affected the bonding strength and interfacial bonding stability, increasing the risk of slippage and incomplete soldering. Comparative Example 2 did not undergo plastic torsional deformation, lacking sufficient deformation energy storage to drive the formation of nanotwins and ultrafine grains. The material strengthening effect was insufficient, resulting in low inherent strength and poor microstructure uniformity. Not only was it difficult to meet the requirements for line-arc stability, but the poor interfacial deformation coordination during bonding also led to slippage and incomplete soldering, and the ultrasonic energy feedback fluctuations were also greater. Comparative Example 3 suffered from excessive torsional deformation, exceeding the reasonable range. This caused the internal defect density of the material to exceed the critical value, resulting in damage such as microcracks. This destroyed the structural integrity of the material, significantly reducing the bonding strength. At the same time, the interfacial bonding quality deteriorated, and the slippage rate and incomplete soldering rate increased significantly, resulting in severely insufficient bonding stability.

[0114] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for producing a high gold bond wire, characterized by, The method comprises the following steps: melting and rapid solidification of raw materials with purity ≥99.999% to prepare gold alloy ingots with gold content ≥99.99%; hot working and multi-pass cold drawing of the gold alloy ingots, with intermediate annealing during cold drawing to obtain intermediate wire with diameter between 50 μm and 200 μm; applying plastic torsional deformation to the intermediate wire, with the degree of plastic torsional deformation being 30 turns / m to 120 turns / m; rapid heat treatment of the intermediate wire subjected to plastic torsional deformation, with the rapid heat treatment temperature being 350℃ to 550℃, the rapid heat treatment time being 2s to 8s, and subsequent rapid cooling; precise drawing of the wire after rapid heat treatment to the final product with diameter of 15 μm to 33 μm.

2. The production process of high gold bond alloy wire according to claim 1, wherein, The raw materials contain total amount ≤0.01% of micro-alloying elements, which are one or more of palladium, cerium and calcium.

3. The production process of high gold bond alloy wire according to claim 2, wherein The micro-alloying elements include 0.001%-0.008% of palladium and 0.0005%-0.002% of cerium by mass percentage.

4. The production process of high gold bond alloy wire according to claim 1, wherein The rapid solidification controls the cooling rate of alloy melt ≥100℃ / s to obtain microcrystalline structure with grain size <50 μm.

5. The production process of high gold bond alloy wire according to claim 1, wherein The intermediate annealing is a rapid current annealing, the current density of the rapid current annealing is 200 A / mm 2 to 400 A / mm2, the current time is 2s-5s.

6. The production process of high gold bond alloy wire according to claim 1, wherein, The degree of plastic torsional deformation is 50 turns / m to 100 turns / m.

7. The production process of high gold bond alloy wire according to claim 1, wherein The rapid heat treatment is performed at a temperature range of 450℃ to 500℃ to obtain recrystallized structure with average grain size <5 μm.

8. The production process of high gold bond alloy wire according to claim 1, wherein, The rapid cooling after rapid heat treatment has a cooling rate ≥100℃ / s.

9. A high gold bond alloy wire produced by the process of any one of claims 1 to 8, characterized in that, The high-gold bonding alloy wire has total gold content ≥99.99%, with diameter of 15 μm to 33 μm, and simultaneously satisfies the following performance indexes: elongation of 5%-9%; resistivity < 2.5 x 10 -8 Ω-m; bonding strength ≥5 cN.

10. The high-gold bonding alloy wire produced by the production process of any one of claims 1-8 is applied to semiconductor packaging.

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