Aluminum-silicon alloy continuously cast rod and method of making, bonding wire and applications

Abstract

The present application relates to the technical field of bonding wire, in particular to an aluminum-silicon alloy continuous casting billet, a preparation method thereof, a bonding wire and application. A mixed material containing an anti-oxidation substance is coated on the surface of metallic aluminum to obtain treated metallic aluminum after drying; elemental silicon is placed in a groove of a graphite pressing rod, and a refining agent solution is filled between the elemental silicon to obtain an elemental silicon feeding device after drying; the treated metallic aluminum is heated to obtain aluminum liquid, and the elemental silicon feeding device is inserted into the aluminum liquid to obtain an aluminum-silicon melt; and the aluminum-silicon melt is continuously cast to obtain an aluminum-silicon alloy continuous casting billet. The present application sets an anti-oxidation layer to avoid oxidation of aluminum during heating, and the anti-oxidation layer can dissolve aluminum oxide on the surface of metallic aluminum after melting to reduce aluminum oxide inclusions; the elemental silicon feeding device can realize integration of aluminum-silicon fusion and internal degassing and impurity removal of the aluminum-silicon melt, and the aluminum-silicon fusion and the degassing and impurity removal have high efficiency; and the obtained continuous casting billet after continuous casting is free of defects and inclusions and has low pore content.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bonding wire, in particular to an aluminum-silicon alloy continuous casting rod blank, a preparation method thereof, a bonding wire and application. BACKGROUND

[0002] The aluminum-silicon alloy bonding wire is an inner lead for microelectronic packaging, and is one of the four basic materials for integrated circuits and semiconductor discrete devices. In recent years, integrated circuits and semiconductor devices develop towards multi-lead, high density and miniaturization, and more and more thin aluminum-silicon wires are required for narrow pitch and long distance bonding.

[0003] The aluminum-silicon alloy bonding wire can be processed by vertical or horizontal continuous casting technology, pure aluminum is mixed with polycrystalline silicon, then melted and directionally solidified to form a cast rod blank, and then processed by multi-pass drawing, and intermediate and final heat treatment until various specifications of finished wire are obtained.

[0004] The ideal aluminum-silicon alloy bonding wire requires good composition uniformity and microstructure uniformity, no defects and inclusions. However, for a long time, people mainly focus on the precise control of the cold forming process of micro wires, and ignore the purification of the alloy melt and the precise control of the solidification structure, so that the micro wires have high breakage rate in the forming process, poor batch stability, wire diameter consistency and hardness uniformity, and low production efficiency and material yield. One of the main reasons is that micro wires are extremely sensitive to 10-50 μm micro inclusions and porosity, and the material deformation capacity is greatly related to the microstructure.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first object of the present application is to provide a preparation method of an aluminum-silicon alloy continuous casting rod blank. By forming an anti-oxidation layer on the surface of the aluminum, the oxidation of the aluminum during heating can be avoided, and the aluminum oxide on the surface of the aluminum can be dissolved after melting, reducing the occurrence of aluminum oxide inclusions with similar density to the aluminum melt in the liquid aluminum melt. By using a silicon feeding device, the refining agent is combined with the elemental silicon, the aluminum-silicon fusion and the internal degassing and inclusion removal of the aluminum-silicon melt can be integrated, and the aluminum-silicon fusion efficiency and the degassing and inclusion removal efficiency are high. Therefore, the aluminum-silicon alloy continuous casting rod blank obtained after continuous casting of the aluminum-silicon melt has no defects and inclusions, low porosity content, low breakage rate of micro wires in the subsequent forming process, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and material yield.

[0007] The second object of the present application is to provide an aluminum-silicon alloy continuous casting rod blank, which has no defects and inclusions, low porosity content, and uniform composition, stable microstructure and good plasticity.

[0008] The third object of the present application is to provide a bonding wire with low wire breakage rate, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and material yield.

[0009] The fourth object of the present application is to provide an application of the bonding wire in integrated circuits and semiconductor devices.

[0010] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0011] The present application first provides a preparation method of an aluminum-silicon alloy continuous casting rod blank, comprising the following steps:

[0012] A mixed material containing an anti-oxidation substance and a solvent is coated on the surface of the metal aluminum, and an anti-oxidation layer is formed after drying to obtain treated metal aluminum; the anti-oxidation substance comprises NaCl and KCl;

[0013] Elemental silicon is placed in a groove at the end of a graphite press rod, and a refining agent solution is filled between the elemental silicon, and an elemental silicon feeding device is obtained after drying;

[0014] After the treated metal aluminum is heated to obtain aluminum liquid, the elemental silicon feeding device is inserted into the aluminum liquid, the elemental silicon in the elemental silicon feeding device enters the aluminum liquid, and an aluminum-silicon melt is obtained after smelting is completed;

[0015] After continuous casting of the aluminum-silicon melt, the aluminum-silicon alloy continuous casting rod blank is obtained.

[0016] Further, the anti-oxidation substance comprises, in terms of mass percentage: 40-45% NaCl, 50-55% KCl, 0-5% NaF, 0-5% Na3AlF6 and 0-5% CaF2.

[0017] Further, the gas pressure of the continuous casting is slightly positive.

[0018] Further, the flow rate of the cooling water used for the continuous casting is 1-1.5 m 3 / h.

[0019] Further, the pulling speed of the continuous casting is 40-60 mm / min.

[0020] Further, the pause time of the continuous casting is 2-5 s.

[0021] Further, before the continuous casting, vacuumization is performed to a vacuum degree of 10-100 Pa, and then inert gas is introduced to maintain the gas pressure of the continuous casting as slightly positive.

[0022] Further, the vertical continuous casting technology is adopted, and the device for melting and continuous casting comprises a graphite crucible, a crystallizer and a graphite plug; the graphite plug is used to plug the inlet end of the crystallizer before the heating melts the treated aluminum metal, so as to realize the homogenization of aluminum-silicon fusion; the graphite plug is opened when the continuous casting is performed.

[0023] Further, the mass ratio of the anti-oxidation substance and the solvent is 2-3:7-8.

[0024] Further, the solvent comprises anhydrous ethanol.

[0025] Further, the preparation method of the mixed material containing the anti-oxidation substance and the solvent comprises: mixing the anti-oxidation substance and the solvent and then ball milling.

[0026] Further, the thickness of the anti-oxidation layer is 0.5-1 mm.

[0027] Further, the elemental silicon comprises polycrystalline silicon.

[0028] Further, the refining agent in the refining agent solution comprises hexachloroethane.

[0029] Further, the mass fraction of the refining agent in the refining agent solution is 60%-80%.

[0030] Further, the mass of the refining agent solution accounts for 5%-20% of the mass of the elemental silicon.

[0031] Further, the temperature of the heating is 800-900℃.

[0032] Further, the feeding device of the elemental silicon is inserted into the elemental silicon, and the distance from the end of the feeding device to the bottom of the aluminum liquid is 10-20 mm.

[0033] Further, the feeding device of the elemental silicon is inserted into the elemental silicon, and the distance from the end of the feeding device to the bottom of the aluminum liquid is 10-20 mm.

[0034] Further, the temperature of the melting is 700-750℃.

[0035] The application further provides an aluminum-silicon alloy continuous casting rod blank, which is prepared by the preparation method.

[0036] Further, the diameter of the aluminum-silicon alloy continuous casting rod blank is 4-8 mm.

[0037] Further, the mass fraction of the silicon element in the aluminum-silicon alloy continuous casting rod blank is 0.5%-1.5%.

[0038] The application further provides an aluminum-silicon alloy continuous casting billet prepared by the preparation method of the aluminum-silicon alloy continuous casting billet, or prepared from the aluminum-silicon alloy continuous casting billet.

[0039] The application further provides application of the bonding wire in integrated circuits and semiconductor devices.

[0040] Compared with the prior art, the application has the following beneficial effects:

[0041] (1) The preparation method of the aluminum-silicon alloy continuous casting billet provided by the application can avoid oxidation of aluminum during heating by arranging an anti-oxidation layer on the surface of the aluminum, and the anti-oxidation layer can dissolve aluminum oxide on the surface of the aluminum after melting, thereby reducing the occurrence of aluminum oxide inclusions with a density close to that of the aluminum melt in the liquid aluminum melt. Meanwhile, the application uses a silicon feeding device to combine the refining agent with the elemental silicon, so that aluminum-silicon fusion and internal degassing and inclusion removal of the aluminum-silicon melt can be integrated, and the aluminum-silicon fusion efficiency and the degassing and inclusion removal efficiency are high. The aluminum-silicon alloy continuous casting billet obtained after continuous casting has no defects and inclusions and low porosity.

[0042] (2) The preparation method of the aluminum-silicon alloy continuous casting billet provided by the application adopts micro-positive pressure combined with strong cooling (controlling the flow of cooling water), low pulling speed (controlling the pulling speed to be 40-60 mm / min), and other continuous casting process parameters, so that the hard silicon cannot be precipitated in time, and thus the obtained continuous casting billet has a dense, uniform and good plasticity structure.

[0043] (3) The preparation method of the aluminum-silicon alloy continuous casting billet provided by the application adopts a two-step degassing method of the refining agent and vacuum, and a two-step inclusion removal method of the anti-oxidation substance and the refining agent, so that the degassing and inclusion removal efficiency is high, and the formed aluminum-silicon alloy continuous casting billet has no defects and inclusions.

[0044] (4) The preparation method of the aluminum-silicon alloy continuous casting billet provided by the application can realize homogenization of aluminum-silicon fusion before continuous casting by arranging the graphite plug, thereby avoiding the problem of inconsistent composition of the head, middle and tail of the obtained continuous casting billet after continuous casting.

[0045] (5) The aluminum-silicon alloy continuous casting billet provided by the application has no defects and inclusions, low porosity, and uniform composition, stable structure and good plasticity.

[0046] (6) The bonding wire provided by the application has low wire breakage rate, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and material yield. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art of the present application, the accompanying drawings needed to be used in the specific embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative effort.

[0048] Figure 1 Structure diagram of the single-element silicon feeding device provided by the present application;

[0049] Figure 2 Structure diagram of the graphite plug used to plug the inlet end of the crystallizer in the smelting process provided by the present application;

[0050] Figure 3 Metallographic picture of the cross section of the continuous casting billet prepared in Example 1 provided by the present application. DETAILED DESCRIPTION

[0051] The technical solutions of the present application will be described clearly and completely in combination with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased on the market.

[0052] If not specifically stated, in the present application, "first aspect", "second aspect", "third aspect", "fourth aspect" and the like are only used for description purposes, and cannot be understood as indicating or implying relative importance or quantity, nor can it be understood as implying the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth" and the like only serve the purpose of non-exhaustive enumeration description, and should be understood as not constituting a closed limitation on the quantity.

[0053] If not specifically stated, the "includes" and "contains" mentioned in the present application mean open-ended, and can also be closed. For example, the "includes" and "contains" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0054] If not specifically stated, in the present application, "one or more" or "at least one" means any one, any two or any two or more of the listed items. Among them, "several" means any two or more.

[0055] In a first aspect, the present application provides a preparation method of an aluminum-silicon alloy continuous casting billet, wherein the aluminum-silicon alloy continuous casting billet comprises an aluminum-silicon alloy continuous casting billet for bonding wires, and the preparation method comprises the following steps:

[0056] A mixed material containing an anti-oxidation substance and a solvent is coated on the surface of the metallic aluminum, and then dried to form an anti-oxidation layer, thereby obtaining the treated metallic aluminum, i.e., the metallic aluminum with the anti-oxidation layer on the surface. The anti-oxidation substance comprises NaCl and KCl.

[0057] It can be understood that the metallic aluminum is elemental aluminum, and the purity thereof is preferably not less than 99.999%. The shape of the elemental aluminum can be blocky or platy, and the present application does not limit the shape.

[0058] The mixed salt of NaCl and KCl has a low melting point, and the covering effect of aluminum melting is good. The melting point of a single component is higher than that of aluminum, and the density of the two substances is small, so they will not enter the aluminum-silicon alloy.

[0059] In some specific embodiments, the drying method for forming the anti-oxidation layer can be baking, and the drying temperature can be 80-100°C, but is not limited thereto.

[0060] The elemental silicon is placed in a groove at the end of a graphite pressure rod, and a refining agent solution is filled between the elemental silicon, and then dried to obtain an elemental silicon feeding device. Figure 1 It is a structural schematic view of the elemental silicon feeding device.

[0061] In some specific embodiments, the shape of the elemental silicon is blocky or granular, and the purity of the elemental silicon is not less than 99.9999%.

[0062] In some specific embodiments, the drying temperature for forming the elemental silicon feeding device is 30-40°C.

[0063] The treated metallic aluminum is heated to completely melt to obtain an aluminum liquid, and then the elemental silicon feeding device is inserted into the aluminum liquid, so that the elemental silicon in the elemental silicon feeding device enters the aluminum liquid, and the aluminum and silicon are fused. After smelting is completed, an aluminum-silicon melt is obtained.

[0064] After continuous casting of the aluminum-silicon melt, the aluminum-silicon alloy continuous casting billet is obtained.

[0065] The preparation method of the aluminum-silicon alloy continuous casting billet provided by the present application sets an anti-oxidation layer on the surface of the metallic aluminum. The anti-oxidation layer can prevent the aluminum from being oxidized when heated, and the anti-oxidation layer can dissolve the aluminum oxide on the surface of the metallic aluminum after melting, thereby reducing the occurrence of aluminum oxide inclusions with a density close to that of the aluminum melt in the liquid aluminum melt.

[0066] Meanwhile, the application adopts a single silicon feeding device, and the refining agent is combined with the single silicon, so that the aluminum-silicon fusion and the gas and impurity removal inside the aluminum-silicon melt are integrated, and the aluminum-silicon fusion efficiency and the gas and impurity removal efficiency are high.

[0067] Therefore, the aluminum-silicon alloy continuous casting rod blank obtained after the aluminum-silicon melt is continuously cast is free of defects and inclusions and has low pore content. Thus, the subsequent micro-wire material has low wire breaking rate in the forming process, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and material yield.

[0068] In some specific embodiments, the anti-oxidation substance comprises, in terms of mass percentage, 40-45% NaCl, 50-55% KCl, 0-5% NaF, 0-5% Na3AlF6 and 0-5% CaF2. The anti-oxidation substance has good covering effect near the eutectic temperature. The NaF, Na3AlF6 and CaF2 can increase the melting temperature, the molten viscosity and the covering effect of the anti-oxidation layer.

[0069] In some specific embodiments, the anti-oxidation substance comprises, in terms of mass percentage, 40-45% NaCl, 50-55% KCl, 0-5% NaF, 0-5% Na3AlF6 and 0-5% CaF2. The anti-oxidation substance has good covering effect near the eutectic temperature. The NaF, Na3AlF6 and CaF2 can increase the melting temperature, the molten viscosity and the covering effect of the anti-oxidation layer.

[0070] In some specific embodiments, the gas pressure of the continuous casting is slightly positive pressure (i.e. slightly greater than 1 atm). The slightly positive pressure facilitates the downward drawing of the continuous casting rod blank.

[0071] In some specific embodiments, the pressure of the slightly positive pressure is 0.11-0.12 MPa.

[0072] In some specific embodiments, the flow rate of the cooling water used in the continuous casting is 1-1.5 m 3 / h; including but not limited to 1 m 3 / h, 1.1 m 3 / h, 1.2 m 3 / h, 1.3 m 3 / h, 1.4 m 3 / h, 1.5 m 3The point value of any one of the above or the range value between any two of them. In the present application, the cooling water flow is large, the heat transfer efficiency is high, the high-efficiency cooling can be realized, the hard silicon precipitation is reduced, and the microstructure density, uniformity and plasticity of the continuous casting rod blank are improved.

[0073] In some specific embodiments, the pulling speed of the continuous casting is 40-60 mm / min; including but not limited to any one of the point values of 40 mm / min, 43 mm / min, 45 mm / min, 48 mm / min, 50 mm / min, 52 mm / min, 55 mm / min, 58 mm / min, 60 mm / min or the range value between any two of them. In the present application, the pulling speed of the continuous casting is low, which is beneficial to avoid the precipitation of hard silicon, thereby improving the microstructure density, uniformity and plasticity of the continuous casting rod blank.

[0074] The hard silicon cannot precipitate in time under the conditions of strong cooling and low pulling speed.

[0075] In the present application, the micro-positive pressure is combined with strong cooling (controlling the flow of cooling water), low pulling speed (controlling the pulling speed to be 40-60 mm / min) and other continuous casting process parameters, so that the hard silicon cannot precipitate in time, and thus the obtained continuous casting rod blank has dense, uniform and good plasticity.

[0076] In some specific embodiments, the pause time of the continuous casting is 2-5 s; including but not limited to any one of the point values of 2 s, 3 s, 4 s, 5 s or the range value between any two of them. The pause is also beneficial to the strong cooling, so that the hard silicon cannot precipitate in time, and thus the obtained continuous casting rod blank has dense, uniform and good plasticity.

[0077] In some specific embodiments, before the continuous casting, the vacuum degree is extracted to 10-100 Pa (including but not limited to any one of the point values of 10 Pa, 15 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa or the range value between any two of them), and then the inert gas is introduced, and the gas pressure of the continuous casting is kept as micro-positive pressure. The inert gas includes but is not limited to argon. The vacuum extraction has the effect of degassing.

[0078] In the present application, the two-step degassing method of refining agent and vacuum is adopted, and the two-step impurity removal method of antioxidant and refining agent is adopted, so that the degassing and impurity removal efficiency is high, and the formed aluminum-silicon alloy continuous casting rod blank is defect-free and inclusion-free.

[0079] In some specific embodiments, the degassing and impurity removal are performed before the continuous casting, and the step of the degassing and impurity removal includes: extracting the aluminum-silicon melt to a vacuum degree of 10-100 Pa, stopping the vacuum extraction when no bubbles are generated in the aluminum-silicon melt, opening the argon valve at the same time, introducing high-purity argon into the furnace, and keeping the micro-positive pressure (slightly greater than 1 atm) in the furnace.

[0080] In some specific embodiments, the heating method comprises induction heating.

[0081] In some specific embodiments, the vertical continuous casting technology is adopted, and the device for melting and continuous casting comprises a graphite crucible, a crystallizer and a graphite plug, wherein the graphite crucible and the crystallizer are connected. Before the heated treated aluminum is melted by heating, the graphite plug is used to block the inlet end of the crystallizer (i.e. the connection between the graphite crucible and the crystallizer), as shown in FIG. 2, and then the induction power is started to heat by induction until the treated aluminum is completely melted and kept at a constant temperature. After that, the single silicon feeding device is used for melting to realize the homogenization of aluminum-silicon fusion, and the aluminum-silicon melt is obtained. When the continuous casting is performed, the graphite plug is opened. Figure 2

[0082] By arranging the graphite plug, the homogenization of aluminum-silicon fusion before continuous casting can be realized, and the problem of inconsistent composition of the head, middle and tail of the continuous casting rod after continuous casting can be avoided.

[0083] By adopting the vertical continuous casting technology, the graphite head after alloying is conveniently located at the lower end of the inlet, and the graphite plug is floated up by the action of the pulling rod to be directly pulled, which is conducive to ensuring the composition uniformity and operation safety.

[0084] In some specific embodiments, the continuous casting comprises the following steps: the flow of the cooling water of the crystallizer is started to be 1-1.5 m 3 / h, the dummy bar is inserted into the crystallizer to lift the graphite plug, the graphite plug is floated on the surface of the melt under the action of the buoyancy, the pulling mechanism is started to adjust the pulling speed to 40-60 mm / min, the pause time is 2-5 s, and the aluminum-silicon alloy continuous casting rod with a diameter of 4-8 mm is obtained.

[0085] In some specific embodiments, the mass ratio of the anti-oxidation substance to the solvent is 2-3:7-8, including but not limited to any one of 2:8, 2.2:7.8, 2.5:7.5, 2.7:7.3 and 3:7, or a range value between any two of them.

[0086] In some specific embodiments, the solvent comprises anhydrous ethanol.

[0087] In some specific embodiments, the preparation method of the mixed material containing the anti-oxidation substance and the solvent comprises: mixing the anti-oxidation substance and the solvent and then ball milling to obtain a paste-like mixed material.

[0088] In some specific embodiments, the thickness of the anti-oxidation layer is 0.5-1 mm.

[0089] In some specific embodiments, the single silicon comprises polycrystalline silicon.​

[0090] In some specific embodiments, the refining agent in the refining agent solution comprises hexachloroethane; and the solvent in the refining agent solution comprises, but is not limited to, ethanol and other organic solvents. That is, the refining agent solution can be an ethanol solution of hexachloroethane.

[0091] In some specific embodiments, the mass fraction of the refining agent in the refining agent solution is 60% to 80%, including but not limited to any one of 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80% or a range value between any two of them.

[0092] In some specific embodiments, the mass of the refining agent solution accounts for 5% to 20% of the mass of the elemental silicon, including but not limited to any one of 5%, 8%, 10%, 13%, 15%, 17%, 20% or a range value between any two of them.

[0093] In some specific embodiments, the heating temperature is 800 to 900℃, including but not limited to any one of 800℃, 820℃, 830℃, 850℃, 870℃, 880℃, 900℃ or a range value between any two of them. Wherein, the heating can be induction heating.

[0094] In some specific embodiments, the single silicon feeding device is inserted into the molten aluminum to a distance of 10 to 20 mm from the bottom of the molten aluminum, that is, the single silicon feeding device is inserted to a distance of 10 to 20 mm from the lowest liquid level of the molten aluminum, wherein the distance includes but is not limited to any one of 10 mm, 12 mm, 13 mm, 15 mm, 18 mm, 20 mm or a range value between any two of them. In this way, the bubbles can be easily escaped from the molten pool, the degassing and impurity removal effect is good, and the homogenization of aluminum-silicon fusion is facilitated.

[0095] In some specific embodiments, the single silicon feeding device is continuously rotated during the smelting. In this way, the bubbles escape more uniformly and densely, the degassing and impurity removal effect is good, and the homogenization of aluminum-silicon fusion is facilitated.

[0096] In some specific embodiments, the smelting temperature is 700 to 750℃, including but not limited to any one of 700℃, 710℃, 720℃, 730℃, 740℃, 750℃ or a range value between any two of them.

[0097] In a second aspect, the application provides an aluminum-silicon alloy continuous casting rod blank, which is prepared by the preparation method of the aluminum-silicon alloy continuous casting rod blank.

[0098] The aluminum-silicon alloy continuous casting rod blank prepared by the application has no defects and inclusions, and low porosity.

[0099] And, the present application regulates the preparation parameters of the aluminum-silicon alloy continuous casting rod blank, and the prepared aluminum-silicon alloy continuous casting rod blank is uniform in composition, stable in structure, and good in plasticity.

[0100] Therefore, in the process of making the bonding wire from the aluminum-silicon alloy continuous casting rod blank, the breakage rate is low, the batch stability, wire diameter consistency and hardness uniformity are good, and the production efficiency and material yield are high.

[0101] In some specific embodiments, the diameter of the aluminum-silicon alloy continuous casting rod blank is 4-8 mm, including but not limited to any one of 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or a range value between any two of them. The continuous casting rod blank with this diameter is drawn into a bonding wire with high efficiency.

[0102] In some specific embodiments, the mass fraction of silicon in the aluminum-silicon alloy continuous casting rod blank is 0.5%-1.5%, for example, 0.6%, 0.8%, 1%, 1.2%, or 1.3%.

[0103] In a third aspect, the present application provides a bonding wire, which is mainly prepared from the aluminum-silicon alloy continuous casting rod blank prepared by the preparation method of the aluminum-silicon alloy continuous casting rod blank, or is prepared from the aluminum-silicon alloy continuous casting rod blank.

[0104] The bonding wire made of the above-mentioned aluminum-silicon alloy continuous casting rod blank has low breakage rate, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and material yield.

[0105] Optionally, the aluminum-silicon alloy continuous casting rod blank is subjected to pass drawing processing, and is subjected to intermediate heat treatment and final heat treatment until it is processed into various specifications of finished wire materials, i.e., a bonding wire.

[0106] In a fourth aspect, the present application provides the application of the bonding wire in integrated circuits and semiconductor devices.

[0107] The application of the bonding wire in integrated circuits and semiconductor devices mainly includes the following aspects: welding and connection, signal transmission and power supply, packaging connection, optical fiber connection and photoelectric conversion, and the bonding wire is also widely used in the fields of microelectronics, LED lighting, aerospace, communication equipment, automobile electronics and smart cards, and the present application does not limit this.

[0108] The embodiments of the present application will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0109] Example 1

[0110] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided by the embodiment comprises the following steps:

[0111] (1) High-purity aluminum raw material treatment: 45% NaCl and 55% KCl by mass percentage are taken as anti-oxidation substances, and ball milling process is adopted to form a paste with ethanol, wherein the mass ratio of the anti-oxidation substances and the solvent is 2.5:7.5. The paste obtained after ball milling is applied to the surface of high-purity aluminum blocks (Al content 99.999wt.%), and then dried at 100°C to form an anti-oxidation layer with a thickness of 1mm, thereby obtaining treated aluminum metal.

[0112] (2) Preparation of elemental silicon feeding device: block-shaped polycrystalline silicon (silicon content 99.9999wt.%) is laid in the grooves at the end of the graphite press rod, and 70% hexachloroethane ethanol solution (i.e. refining agent solution) is filled between the block-shaped polycrystalline silicon, wherein the mass of the hexachloroethane ethanol solution accounts for 20% of the mass of the elemental silicon, and then dried at 35°C to obtain the elemental silicon feeding device.

[0113] (3) High-purity aluminum melting: vertical continuous casting technology is adopted, the inlet end of the crystallizer is blocked with a graphite plug, and then the induction power is started for induction heating until the treated aluminum metal is completely melted, wherein the heating temperature is 850°C, and the aluminum liquid is obtained.

[0114] (4) Aluminum-silicon melting: the elemental silicon feeding device is inserted into the aluminum liquid 10mm from the bottom, and the graphite press rod of the elemental silicon feeding device is rotated until no bubbles are generated on the liquid surface, thereby completing the melting of the aluminum-silicon melt, wherein the melting temperature is 730°C.

[0115] (5) Melt degassing and impurity removal: the aluminum-silicon melt is vacuumized to a vacuum degree of 50Pa, and the vacuumization is stopped when no bubbles are generated in the aluminum-silicon melt, while the argon valve is opened to pass high-purity argon into the furnace, and a slight positive pressure (0.11Mpa) is maintained in the furnace.

[0116] (6) Continuous casting: the cooling water flow of the crystallizer is started to 1.5m 3 / h, the dummy bar is inserted into the crystallizer and the graphite plug is lifted up, the graphite plug floats on the surface of the melt under the action of the buoyancy, the traction mechanism is started to adjust the traction speed to 40mm / min, and the pause time is 4s, thereby obtaining a continuous casting rod blank with a diameter of 5mm. The mass fraction of silicon in the continuous casting rod blank is 1%.

[0117] Example 2

[0118] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (1), the anti-oxidation substance is 40% NaCl, 55% KCl and 5% NaF in terms of mass percentage.

[0119] Embodiment 3

[0120] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (1), the anti-oxidation substance is 45% NaCl, 50% KCl and 5% Na3AlF6 in terms of mass percentage.

[0121] Embodiment 4

[0122] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (1), the anti-oxidation substance is 43% NaCl, 52% KCl and 5% CaF2 in terms of mass percentage.

[0123] Embodiment 5

[0124] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (1), the anti-oxidation substance is 40% NaCl, 50% KCl, 3% NaF, 4% Na3AlF6 and 3% CaF2 in terms of mass percentage.

[0125] Embodiment 6

[0126] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (6), the cooling water flow rate of the continuous casting is 1 m 3 / h, the pulling speed is 60 mm / min, and the pause time is 2 s.

[0127] Embodiment 7

[0128] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is basically the same as that in Embodiment 1, except that in step (4), the elemental silicon feeding device is inserted to a position 20 mm away from the bottom of the aluminum liquid.

[0129] Embodiment 8

[0130] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this embodiment includes the following steps:

[0131] (1) High purity aluminum raw material treatment: 42% NaCl and 58% KCl by mass percentage were weighed as anti-oxidation substances, and ball milling process was used to form a paste with anhydrous ethanol, wherein the mass ratio of anti-oxidation substances to solvent was 3:7. The paste obtained after ball milling was applied to the surface of high purity aluminum blocks (Al content 99.999wt.%), and then dried at 80°C to form an anti-oxidation layer with a thickness of 0.5mm, thereby obtaining treated aluminum metal.

[0132] (2) Preparation of elemental silicon feeding device: block-shaped polycrystalline silicon (silicon content 99.9999wt.%) was laid in the grooves at the end of the graphite press rod, and a mass fraction of 70% hexachloroethane ethanol solution (i.e. refining agent solution) was filled between the block-shaped polycrystalline silicon, wherein the mass of the hexachloroethane ethanol solution accounted for 10% of the mass of the elemental silicon, and then dried at a temperature of 40°C to obtain an elemental silicon feeding device.

[0133] (3) High purity aluminum melting: vertical continuous casting technology was used, the inlet end of the crystallizer was blocked with a graphite plug, and then the induction power was started for induction heating until the treated aluminum metal was completely melted, wherein the heating temperature was 900°C, thereby obtaining aluminum liquid.

[0134] (4) Aluminum-silicon fusion: the elemental silicon feeding device was inserted into the aluminum liquid 15mm from the bottom, and the graphite press rod of the elemental silicon feeding device was rotated until no bubbles were emitted from the liquid surface, thereby completing the melting of the aluminum-silicon melt, wherein the melting temperature was 750°C.

[0135] (5) Melt degassing and impurity removal: the aluminum-silicon melt was vacuumed to a vacuum degree of 20Pa, and the vacuuming was stopped when no bubbles were emitted from the aluminum-silicon melt, while the argon valve was opened to pass high-purity argon into the furnace, and a slight positive pressure (0.115Mpa) was maintained in the furnace.

[0136] (6) Continuous casting: the flow rate of the crystallizer cooling water was started to 1.3m 3 / h, the dummy bar was inserted into the crystallizer and the graphite plug was lifted, the graphite plug floated on the surface of the melt under the action of buoyancy, the traction mechanism was started to adjust the traction speed to 50mm / min, and the pause time was 5s, thereby obtaining a continuous casting rod blank with a diameter of 7mm. The mass fraction of silicon element in the continuous casting rod blank was 1%.

[0137] Example 9

[0138] The preparation method of the aluminum-silicon alloy continuous casting rod blank provided in this example is basically the same as that of Example 1, except that the mass fraction of silicon element in the prepared continuous casting rod blank is 0.8%.

[0139] Comparative Example 1

[0140] The preparation method of the aluminum-silicon alloy continuous casting billet provided by the present comparative example is basically the same as that of Example 1, except that step (1) is not performed, and the treated aluminum metal in step (3) is replaced by high-purity aluminum blocks (Al content 99.999 wt.%) (aluminum-silicon ratio same as Example 1).

[0141] Comparative Example 2

[0142] The preparation method of the aluminum-silicon alloy continuous casting billet provided by the present comparative example is basically the same as that of Example 1, except that step (2) is not performed, and the blocky polysilicon in step (4) is directly added into the aluminum liquid (aluminum-silicon ratio same as Example 1) (the mass of the blocky polysilicon in step (2) of Example 1).

[0143] Comparative Example 3

[0144] The preparation method of the aluminum-silicon alloy continuous casting billet provided by the present comparative example is basically the same as that of Example 1, except that in step (6), the cooling water flow rate of the continuous casting is 0.1 m 3 / h, the pulling speed is 100 mm / min, and the pause time is 1 s.

[0145] Comparative Example 4

[0146] The preparation method of the aluminum-silicon alloy continuous casting billet provided by the present comparative example is basically the same as that of Example 1, except that in step (1), KCl is not added (replaced by an equal mass of NaCl, i.e., the total mass of the antioxidant is unchanged).

[0147] Experimental Example

[0148] The substrate tensile test refers to GB / T228.1-2010 “Metallic Materials Tensile Test Part 1: Room Temperature Test Method”. The continuous casting billets of Example 1 and Comparative Examples 1-4 are subjected to room temperature tensile test at a speed of 5 mm / min using an MTS C45.105 type microcomputer-controlled mechanical electronic universal testing machine. The tensile property test results are the average values of 5 samples. The results of the aluminum-silicon alloy continuous casting billets are shown in Table 1.

[0149] Table 1 Tensile Property Test Results

[0150]

[0151] Among them, the excellent wire drawing performance is the characteristic mark of micro-wire drawing. In order to compare the advantages and disadvantages of aluminum-silicon alloy continuous casting billets, the wire breaking rate index of drawing to finished product can be used, i.e., the average wire weight that can be drawn per break.

[0152] Figure 3 The metallographic picture of the cross section of the continuous casting billet prepared in Example 1 can be seen that the aluminum-silicon alloy continuous casting billet has no inclusions and pores.

[0153] By Figure 3 As can be seen from Table 1, the aluminum-silicon alloy continuous casting billets prepared by the method of the present application have no defects and inclusions, low porosity content, uniform composition, stable structure, good plasticity and good drawing performance.

[0154] Comparative Example 1 does not add the anti-oxidizing substance, and the removal effect of the aluminum oxide impurities is not as complete as that of Example 1, and the drawing performance is poor.

[0155] Comparative Example 2 does not use the elemental silicon feeding device and directly adds the polycrystalline silicon, and the degassing and impurity removal effect is not as ideal as that of Example 1, and the drawing performance is poor.

[0156] Comparative Example 3 uses unsuitable continuous casting parameters, and the low-temperature solid solubility of silicon precipitates causes segregation, and the drawing performance is poor.

[0157] Comparative Example 4 only uses NaCl as the anti-oxidizing substance, and the melting temperature is relatively high compared with the melting point of aluminum, the covering effect is poor compared with Example 1, which leads to a significant decrease in performance, and the drawing performance is poor.

[0158] In summary, the aluminum-silicon alloy continuous casting billets prepared by the method of the present application have no defects and inclusions, low porosity content, and uniform composition, stable structure, good plasticity and good drawing performance.

[0159] Although the present application has been illustrated and described with reference to specific embodiments, it is realized that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting; those skilled in the art should understand that the technical solutions recorded in the above examples can be modified, or some or all of the technical features can be replaced equivalently without departing from the spirit and scope of the present application; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that all these replacements and modifications within the scope of the present application are included in the appended claims.

Claims

1. A method for producing an aluminium silicon alloy continuously cast billet, characterized in that, The method comprises the following steps: coating a mixture of anti-oxidation substances and solvent on the surface of the metal aluminum to form an anti-oxidation layer after drying, thereby obtaining treated metal aluminum; the anti-oxidation substances comprise NaCl and KCl; putting elemental silicon into grooves at the end of a graphite press rod, and filling a refining agent solution between the elemental silicon, thereby obtaining an elemental silicon feeding device after drying; after heating the treated metal aluminum to obtain aluminum liquid, inserting the elemental silicon feeding device into the aluminum liquid, so that the elemental silicon in the elemental silicon feeding device enters the aluminum liquid, thereby obtaining aluminum silicon melt after smelting; after continuous casting of the aluminum silicon melt, obtaining the aluminum silicon alloy continuous casting rod blank; the anti-oxidation substances comprise, in terms of mass percentage, 40-45% NaCl, 50-55% KCl, 0-5% NaF, 0-5% Na3AlF6 and 0-5% CaF2; the gas pressure of the continuous casting is slightly positive; The flow rate of the cooling water used for the continuous casting is 1 to 1.5 m 3 / h; the pulling speed of the continuous casting is 40-60 mm / min; the mass ratio of the anti-oxidation substances to the solvent is 2-3:7-8; the thickness of the anti-oxidation layer is 0.5-1 mm.

2. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, the pause time of the continuous casting is 2-5 s.

3. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, before the continuous casting, vacuumizing to a vacuum degree of 10-100 Pa, and then introducing inert gas to maintain the gas pressure of the continuous casting as slightly positive.

4. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, using vertical continuous casting technology, the devices used for smelting and continuous casting comprise a graphite crucible, a crystallizer and a graphite plug; before heating the treated metal aluminum to melt, plugging the graphite plug into the inlet end of the crystallizer to realize homogenization of aluminum silicon smelting; opening the graphite plug when performing the continuous casting.

5. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, at least one of the following conditions is met: (1) the solvent comprises anhydrous ethanol; (2) the preparation method of the mixture of anti-oxidation substances and solvent comprises mixing the anti-oxidation substances and the solvent and then ball milling.

6. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, at least one of the following conditions is met: (1) the elemental silicon comprises polycrystalline silicon; (2) the refining agent in the refining agent solution comprises hexachloroethane; (3) the mass fraction of the refining agent in the refining agent solution is 60-80%; (4) the mass of the refining agent solution accounts for 5-20% of the mass of the elemental silicon.

7. The method of producing an aluminum silicon alloy continuous cast billet according to claim 1, characterized by, at least one of the following conditions is met: (1) the temperature of the heating is 800-900℃; (2) the end portion containing the elemental silicon is 10-20 mm away from the bottom of the aluminum liquid when the elemental silicon feeding device is inserted into the aluminum liquid; (3) rotating the elemental silicon feeding device during the smelting; (4) the temperature of the smelting is 700-750℃.

8. An aluminium silicon alloy continuously cast billet, characterised in that, obtained by the preparation method of the aluminum silicon alloy continuous casting rod blank according to any one of claims 1-7.

9. The aluminium silicon alloy continuously cast billet according to claim 8, c h a r a c t e r i s e d in that the diameter of the aluminum silicon alloy continuous casting rod blank is 4-8 mm.

10. The aluminium silicon alloy continuously cast billet according to claim 8, c h a r a c t e r i s e d in that the mass fraction of the silicon element in the aluminum silicon alloy continuous casting rod blank is 0.5%-1.5%.

11. Bonding wire, characterized in that mainly obtained by the preparation method of the aluminum silicon alloy continuous casting rod blank according to any one of claims 1-7, or prepared by the aluminum silicon alloy continuous casting rod blank according to any one of claims 8-10.

12. Use of the bonding wire of claim 11 in integrated circuits and semiconductor devices.

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