Aluminum-silicon alloy continuous casting rod blank, preparation method thereof, bonding wire and application

Abstract

The invention relates to the technical field of bonding wires, in particular to an aluminum-silicon alloy continuous casting rod blank, a preparation method of the aluminum-silicon alloy continuous casting rod blank, a bonding wire and application. The method comprises the following steps: coating a mixed material containing an anti-oxidation substance on the surface of metal aluminum, and drying to obtain treated metal aluminum; monatomic silicon is placed in a groove of a graphite pressing rod, a refining agent solution is filled between the monatomic silicon, and the monatomic silicon feeding device is obtained after drying; heating the treated metal aluminum to obtain molten aluminum, and extending a monatomic silicon feeding device into the molten aluminum to obtain an aluminum-silicon melt; and continuously casting the aluminum-silicon melt to obtain an aluminum-silicon alloy continuous casting rod blank. The anti-oxidation layer is arranged, oxidation during aluminum heating can be avoided, aluminum oxide on the surface of metal aluminum can be dissolved after the anti-oxidation layer is molten, and aluminum oxide inclusion is reduced; by adopting the monatomic silicon feeding device, integration of aluminum-silicon fusion and degassing and impurity removal in the aluminum-silicon melt can be realized, and the aluminum-silicon fusion and degassing and impurity removal efficiency is high; a continuous casting rod blank obtained after continuous casting is free of defects and inclusions and low in air hole content.

Description

Technical Field

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

[0002] As the inner lead for microelectronic packaging, aluminum-silicon alloy bonding wire is one of the four basic materials for integrated circuits and discrete semiconductor devices. In recent years, integrated circuits and semiconductor devices have developed towards multi-lead packaging, high density, and miniaturization, requiring the use of increasingly fine aluminum-silicon wires for narrow pitch and long distance bonding.

[0003] Aluminum-silicon alloy bonding wire can be processed by vertical or horizontal continuous casting technology. Pure aluminum is mixed with polycrystalline silicon, then smelted and directionally solidified to form a cast rod blank, which is then drawn through multiple passes, with intermediate and final heat treatments, until it is processed into finished wires of various specifications.

[0004] The ideal aluminum-silicon alloy bonding wire requires good composition uniformity and structural uniformity, without defects and inclusions. However, for a long time, people have mainly focused on the precise control of the cold forming process of fine wires, while ignoring the purification of the alloy melt and the precise control of the solidification structure. As a result, the fine wire has a high wire breakage rate during the forming process, poor batch stability, wire diameter consistency, and hardness uniformity, and low production efficiency and yield rate. One of the main reasons is that the fine wire is extremely sensitive to the content of fine inclusions and pores of 10 to 50 μm, and the material deformation ability is closely related to its microstructure.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first purpose of the present invention is to provide a method for preparing an aluminum-silicon alloy continuous casting rod blank, which can avoid oxidation of aluminum when heated by forming an anti-oxidation layer on the surface of metal aluminum, and can dissolve aluminum oxide on the surface of metal aluminum after melting, thereby reducing the appearance of aluminum oxide inclusions with a density similar to that of the aluminum melt in the liquid aluminum melt; a single-element silicon feeding device is used to combine a refining agent with single-element silicon, so that aluminum-silicon fusion and degassing and impurity removal inside the aluminum-silicon melt can be integrated, and the aluminum-silicon fusion efficiency and degassing and impurity 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 pore content, low wire breakage rate in the subsequent fine wire forming process, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and yield rate.

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

[0008] The third object of the present invention 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 yield rate.

[0009] A fourth object of the present invention is to provide applications of bonding wires in integrated circuits and semiconductor devices.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] The present invention first provides a method for preparing an aluminum-silicon alloy continuous casting rod billet, 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 the treated metal aluminum; the anti-oxidation substance includes NaCl and KCl;

[0013] Placing elemental silicon in the groove at the end of the graphite pressure rod, and filling the space between the elemental silicon with a refining agent solution, and obtaining an elemental silicon feeding device after drying;

[0014] After heating the treated metal aluminum to obtain aluminum liquid, extending the elemental silicon feeding device into the aluminum liquid so that the elemental silicon in the elemental silicon feeding device enters the aluminum liquid, and obtaining an aluminum silicon melt after smelting;

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

[0016] Furthermore, the antioxidant substances include, by mass percentage, 40% to 45% NaCl, 50% to 55% KCl, 0% to 5% NaF, 0% to 5% Na3AlF6 and 0% to 5% CaF2.

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

[0018] Furthermore, the flow rate of cooling water used in the continuous casting is 1 to 1.5 m 3 / h.

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

[0020] Furthermore, the pause time of the continuous casting is 2 to 5 seconds.

[0021] Furthermore, before the continuous casting, the vacuum is evacuated to a vacuum degree of 10-100 Pa, and then an inert gas is introduced to maintain the gas pressure of the continuous casting at a slightly positive pressure.

[0022] Furthermore, a vertical continuous casting technology is adopted, and the devices used for the smelting and the continuous casting include a graphite crucible, a crystallizer and a graphite plug; before the heating to melt the treated metal aluminum, the graphite plug is used to plug the inlet end of the crystallizer to achieve homogenization of the aluminum-silicon fusion; the graphite plug is opened when the continuous casting is carried out.

[0023] Furthermore, the mass ratio of the antioxidant substance to the solvent is 2-3:7-8.

[0024] Furthermore, the solvent includes anhydrous ethanol.

[0025] Furthermore, the method for preparing the mixed material containing the anti-oxidation substance and the solvent comprises: mixing the anti-oxidation substance and the solvent and then ball milling them.

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

[0027] Furthermore, the single-element silicon includes polycrystalline silicon.

[0028] Furthermore, the refining agent in the refining agent solution includes hexachloroethane.

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

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

[0031] Furthermore, the heating temperature is 800-900°C.

[0032] Furthermore, the elemental silicon feeding device extends to the end containing the elemental silicon and is 10 to 20 mm away from the bottom of the aluminum liquid.

[0033] Furthermore, during the smelting process, the elemental silicon feeding device is rotated.

[0034] Furthermore, the smelting temperature is 700-750°C.

[0035] The present invention also provides an aluminum-silicon alloy continuous casting rod blank, which is prepared by adopting the preparation method of the aluminum-silicon alloy continuous casting rod blank.

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

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

[0038] The present invention further provides a bonding wire, which is mainly prepared from the aluminum-silicon alloy continuous casting rod blank obtained by the preparation method of the aluminum-silicon alloy continuous casting rod blank, or prepared from the aluminum-silicon alloy continuous casting rod blank.

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

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

[0041] (1) The method for preparing the aluminum-silicon alloy continuous casting rod blank provided by the present invention provides an anti-oxidation layer on the surface of the metal 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 metal aluminum after melting, thereby reducing the appearance of aluminum oxide inclusions with a density similar to that of the aluminum melt in the liquid aluminum melt. At the same time, the present invention adopts a single silicon feeding device, combines the refining agent with the single silicon, and can realize the integration of aluminum-silicon fusion and degassing and impurity removal inside the aluminum-silicon melt, with high aluminum-silicon fusion efficiency and degassing and impurity removal efficiency. The aluminum-silicon alloy continuous casting rod blank obtained after continuous casting has no defects and inclusions, and has a low pore content.

[0042] (2) The method for preparing the aluminum-silicon alloy continuous casting rod blank provided by the present invention adopts continuous casting process parameters such as slight positive pressure combined with strong cooling (controlling the flow rate of cooling water), low pulling speed (controlling the pulling speed to be 40-60 mm / min), etc., so that hard silicon has no time to precipitate. Therefore, the obtained continuous casting rod blank has a dense, uniform structure and good plasticity.

[0043] (3) The preparation method of the aluminum-silicon alloy continuous casting rod blank provided by the present invention adopts a two-step degassing method using a refining agent and a vacuum method, and a two-step decontamination method using an anti-oxidation substance and a refining agent method. The degassing and impurity removal efficiency is high, and the formed aluminum-silicon alloy continuous casting rod blank is free of defects and inclusions.

[0044] (4) The method for preparing the aluminum-silicon alloy continuous casting rod blank provided by the present invention can achieve the homogenization of the aluminum-silicon fusion before continuous casting by setting a graphite plug, thereby avoiding the problem of inconsistent composition of the head, middle and tail of the continuous casting rod blank obtained after continuous casting.

[0045] (5) The aluminum-silicon alloy continuous casting rod blank provided by the present invention has no defects and inclusions, low pore content, uniform composition, stable structure and good plasticity.

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

[0047] 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.

[0048] Figure 1 This is a schematic diagram of the structure of the elemental silicon feeding device provided by the present invention;

[0049] Figure 2 A schematic diagram of the structure of using a graphite plug to plug the inlet end of the crystallizer during the smelting process provided by the present invention;

[0050] Figure 3 This is a metallographic picture of the cross section of the continuous casting rod blank prepared in Example 1 provided by the present invention. DETAILED DESCRIPTION

[0051] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0052] If there is no special explanation, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0053] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0054] If there is no special explanation, in the present invention, "one or more" or "at least one" refers to any one, any two or more of the listed items. Among them, "several" refers to any two or more of the listed items.

[0055] In a first aspect, the present invention provides a method for preparing an aluminum-silicon alloy continuous casting rod blank, wherein the aluminum-silicon alloy continuous casting rod blank includes a continuous casting rod blank for an aluminum-silicon alloy bonding wire, 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 metal aluminum, and then dried to form an anti-oxidation layer to obtain treated metal aluminum, that is, metal aluminum with an anti-oxidation layer on the surface. The anti-oxidation substance includes NaCl and KCl.

[0057] It can be understood that the metallic aluminum is single-element aluminum, and its purity is preferably not less than 99.999%. Its shape can be block, plate, etc., and the present invention is not limited to this.

[0058] The mixed salt of NaCl and KCl has a low melting point and has a good aluminum melting coverage effect. The melting point of a single component is higher than the melting point of aluminum. These two substances have a low density and will not enter the aluminum-silicon alloy.

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

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

[0061] In some specific implementations, the single silicon is in a block, granular, or the like, and the purity of the single silicon is not less than 99.9999%.

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

[0063] The treated metallic aluminum is heated to completely melt it to obtain aluminum liquid, and then the elemental silicon feeding device is extended into the aluminum liquid to allow the elemental silicon in the elemental silicon feeding device to enter the aluminum liquid to fuse the aluminum and silicon. After the smelting is completed, an aluminum silicon melt is obtained.

[0064] After the aluminum-silicon melt is continuously cast, the aluminum-silicon alloy continuous casting rod blank is obtained.

[0065] The method for preparing an aluminum-silicon alloy continuous casting rod billet provided by the present invention provides an anti-oxidation layer on the surface of the metal 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 metal aluminum after melting, thereby reducing the presence of aluminum oxide inclusions with a density similar to that of the aluminum melt in the liquid aluminum melt.

[0066] At the same time, the present invention adopts a single-element silicon feeding device to combine the refining agent with the single-element silicon, which can realize the integration of aluminum-silicon fusion and degassing and impurity removal inside the aluminum-silicon melt, and the aluminum-silicon fusion efficiency and degassing and impurity removal efficiency are high.

[0067] Therefore, the aluminum-silicon alloy continuous casting rod blank obtained after continuous casting of the aluminum-silicon melt has no defects and inclusions, and has a low porosity content. Therefore, the subsequent fine wire has a low wire breakage rate during the forming process, good batch stability, wire diameter consistency and hardness uniformity, and high production efficiency and yield rate.

[0068] In some specific embodiments, the anti-oxidation material includes, by mass percentage, 40% to 45% NaCl, 50% to 55% KCl, 0% to 5% NaF, 0% to 5% Na3AlF6 and 0% to 5% CaF2. The anti-oxidation material has a good covering effect near the eutectic temperature. Among them, NaF, Na3AlF6 and CaF2 can increase the melting temperature, melt viscosity and covering effect of the anti-oxidation layer.

[0069] Wherein, NaCl includes but is not limited to any one of 40%, 41%, 42%, 43%, 44%, 45% by mass percentage or any range between two of them; KCl includes but is not limited to any one of 50%, 51%, 52%, 53%, 54%, 55% by mass percentage or any range between two of them; NaF includes but is not limited to any one of 0%, 1%, 2%, 3%, 4%, 5% by mass percentage or any range between two of them; Na3AlF6 includes but is not limited to any one of 0%, 1%, 2%, 3%, 4%, 5% by mass percentage or any range between two of them; CaF2 includes but is not limited to any one of 0%, 1%, 2%, 3%, 4%, 5% by mass percentage or any range between two of them.

[0070] In some specific implementations, the continuous casting gas pressure is a slightly positive pressure (ie, slightly greater than 1 atmosphere). The slightly positive pressure facilitates the downward leading of the continuous casting billet rod.

[0071] In some specific implementations, the slight positive pressure is 0.11-0.12 MPa.

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

[0073] In some specific embodiments, the continuous casting traction speed is 40-60 mm / min; including but not limited to any point value 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 any range value between two of them. The continuous casting traction speed in the present invention is low, which is conducive to avoiding the precipitation of hard silicon, thereby improving the structural density, uniformity and plasticity of the continuous casting rod blank.

[0074] Strong cooling and low pulling speed will prevent the hard silicon from precipitating in time.

[0075] The present invention adopts continuous casting process parameters such as slight 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), etc., so that hard silicon has no time to precipitate, so the obtained continuous casting rod blank has dense, uniform structure and good plasticity.

[0076] In some specific implementations, the pause time of the continuous casting is 2 to 5 seconds, including but not limited to any point value of 2 seconds, 3 seconds, 4 seconds, and 5 seconds, or a range of values ​​between any two of them. The pause also facilitates strong cooling, so that the hard silicon does not have time to precipitate, so the obtained continuous casting rod blank has a dense, uniform structure and good plasticity.

[0077] In some specific embodiments, before the continuous casting, the vacuum is evacuated to a vacuum degree of 10 to 100 Pa (including but not limited to any point value of 10Pa, 15Pa, 20Pa, 30Pa, 40Pa, 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa or any range value between two of them), and then an inert gas is introduced to keep the gas pressure of the continuous casting at a slightly positive pressure. The inert gas includes but is not limited to argon. Vacuuming has a degassing effect.

[0078] The invention adopts a two-step method of refining agent and vacuum for degassing, and an anti-oxidation substance and refining agent for decontamination, and has high degassing and decontamination efficiency, and the formed aluminum-silicon alloy continuous casting rod blank has no defects and inclusions.

[0079] In some specific implementations, degassing and impurity removal are performed before the continuous casting, and the degassing and impurity removal steps include: evacuating the aluminum silicon melt to a vacuum degree of 10 to 100 Pa, stopping the vacuuming when no bubbles emerge from the aluminum silicon melt, and simultaneously opening the argon valve to pass high-purity argon gas into the furnace, and maintaining a slightly positive pressure in the furnace (slightly greater than 1 atmosphere).

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

[0081] In some specific embodiments, a vertical continuous casting technology is used, and the smelting and continuous casting devices include a graphite crucible, a crystallizer, and a graphite plug, wherein the graphite crucible and the crystallizer are connected. Before the heating to melt the treated metal aluminum, the graphite plug is plugged at the inlet end of the crystallizer (i.e., the connection between the graphite crucible and the crystallizer), see Figure 2 As shown, the induction power supply is then started to perform induction heating until the treated metal aluminum is completely melted and kept warm, and then the single silicon feeding device is put into the smelting to achieve homogenization of aluminum-silicon fusion to obtain the aluminum-silicon melt. When performing the continuous casting, the graphite plug can be opened.

[0082] The present invention can realize the homogenization of aluminum-silicon fusion before continuous casting by arranging the graphite plug, thereby avoiding the problem of inconsistent components of the head, middle and tail of the continuous casting rod blank obtained after continuous casting.

[0083] The vertical continuous casting technology is adopted to facilitate the placement of the graphite head at the lower inlet after smelting and alloying. Under the action of the traction rod, the graphite plug floats up and is directly pulled, which is beneficial to ensure the uniformity of composition and operation safety.

[0084] In some specific implementations, the continuous casting comprises the following steps: starting the crystallizer cooling water flow rate to 1-1.5 m 3 / h, insert the ingot rod into the crystallizer and lift up the graphite plug. Under the action of buoyancy, the graphite plug floats on the surface of the melt, start the traction mechanism and adjust the traction speed to 40-60mm / min, pause for 2-5s, and obtain the aluminum-silicon alloy continuous casting rod billet with a diameter of 4-8mm.

[0085] In some specific embodiments, the mass ratio of the antioxidant substance to the solvent is 2-3:7-8, including but not limited to any point value of 2:8, 2.2:7.8, 2.5:7.5, 2.7:7.3, 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 method for preparing the mixed material containing the antioxidant substance and the solvent comprises: mixing the antioxidant substance and the solvent and then ball milling them to obtain a paste-like mixed material.

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

[0089] In some specific embodiments, the elemental silicon includes polycrystalline silicon.

[0090] In some specific embodiments, the refining agent in the refining agent solution includes hexachloroethane; the solvent in the refining agent solution includes but is not limited to organic solvents such as ethanol, 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 point value 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 point value of 5%, 8%, 10%, 13%, 15%, 17%, 20% or a range between any two of them.

[0093] In some specific embodiments, the heating temperature is 800-900° C., including but not limited to any point value of 800° C., 820° C., 830° C., 850° C., 870° C., 880° C., 900° C., or any range value between two of them. The heating may be induction heating.

[0094] In some specific embodiments, the distance between the end of the elemental silicon feeding device extending into the aluminum liquid and the bottom of the aluminum liquid is 10 to 20 mm, that is, the elemental silicon feeding device extends into the lowest liquid level of the aluminum liquid by 10 to 20 mm, wherein the distance includes but is not limited to any point value of 10 mm, 12 mm, 13 mm, 15 mm, 18 mm, and 20 mm or any range value between the two. This facilitates the escape of bubbles from the molten pool, has a good degassing and impurity removal effect, and is conducive to the homogenization of aluminum-silicon fusion.

[0095] In some specific implementations, during the smelting process, the elemental silicon feeding device is continuously rotated, so that the rotating bubbles escape more evenly and densely, the degassing and impurity removal effect is good, and it is beneficial to the homogenization of aluminum-silicon fusion.

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

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

[0098] The aluminum-silicon alloy continuous casting rod blank prepared by the invention has no defects and inclusions and has low pore content.

[0099] Furthermore, the present invention adjusts and controls the preparation parameters of the aluminum-silicon alloy continuous casting rod billet, so that the aluminum-silicon alloy continuous casting rod billet obtained has uniform composition, stable structure and good plasticity.

[0100] Therefore, in the process of making bonding wires from aluminum-silicon alloy continuous casting rod billets, the wire breakage rate is low, the batch stability, wire diameter consistency and hardness uniformity are good, and the production efficiency and yield rate 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 point value of 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or any range value between two of them. The continuous casting rod blank with this diameter is used to draw the bonding wire with high efficiency.

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

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

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

[0105] Optionally, the aluminum-silicon alloy continuous casting rod blank is subjected to a drawing process, and is subjected to an intermediate heat treatment and a final heat treatment until it is processed into finished wire rods of various specifications, that is, a bonding wire is obtained.

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

[0107] The application of 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. Bonding wire is also widely used in microelectronics, LED lighting, aerospace, communication equipment, automotive electronics and smart cards, etc., which are not limited in the present invention.

[0108] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0109] Example 1

[0110] The method for preparing the aluminum-silicon alloy continuous casting rod blank provided in this embodiment comprises the following steps:

[0111] (1) Treatment of high-purity aluminum raw materials: 45% NaCl and 55% KCl were weighed as antioxidants in percentage by mass, and the mixture was ball-milled with anhydrous ethanol to form a paste, wherein the mass ratio of the antioxidant to the solvent was 2.5:7.5. The paste-like mixed material obtained after ball milling was applied to the surface of a high-purity aluminum block (Al content 99.999 wt.%), and then dried at 100° C. to form an antioxidant layer with a thickness of 1 mm, thereby obtaining treated metal aluminum.

[0112] (2) Preparation of a silicon feeding device: Block polycrystalline silicon (silicon content 99.9999 wt.%) is spread flat in the groove at the end of a graphite pressure rod, and a 70% by mass hexachloroethane ethanol solution (i.e., a refining agent solution) is filled between the block polycrystalline silicon, wherein the mass of the hexachloroethane ethanol solution accounts for 20% of the mass of the silicon. The block polycrystalline silicon is then dried at 35°C to obtain a silicon feeding device.

[0113] (3) High-purity aluminum melting: vertical continuous casting technology is used, and a graphite plug is used to plug the inlet end of the crystallizer. Then the induction power supply is started, and induction heating is performed until the treated metal aluminum is completely melted. The heating temperature is 850°C to obtain aluminum liquid.

[0114] (4) Aluminum-silicon fusion: The silicon feeding device is inserted into the aluminum liquid at a distance of 10 mm from the bottom, and the graphite pressure rod of the silicon feeding device is rotated until no bubbles emerge from the liquid surface, thereby completing the smelting of the aluminum-silicon melt. The smelting temperature is 730°C.

[0115] (5) Degassing and impurity removal of the melt: Evacuate the aluminum silicon melt to a vacuum degree of 50Pa. Stop evacuating the aluminum silicon melt when no bubbles emerge. At the same time, open the argon valve to pass high-purity argon gas into the furnace and maintain a slight positive pressure (0.11Mpa) in the furnace.

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

[0117] Example 2

[0118] The method for preparing 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 substances are calculated by mass percentage as follows: 40% NaCl, 55% KCl and 5% NaF.

[0119] Example 3

[0120] The method for preparing 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 substances are calculated by mass percentage as follows: 45% NaCl, 50% KCl and 5% Na3AlF6.

[0121] Example 4

[0122] The method for preparing 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 substances are calculated by mass percentage as follows: 43% NaCl, 52% KCl and 5% CaF2.

[0123] Example 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 Example 1, except that in step (1), the anti-oxidation substances are calculated by mass percentage as follows: 40% NaCl, 50% KCl, 3% NaF, 4% Na3AlF6 and 3% CaF2.

[0125] Example 6

[0126] The method for preparing 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 1m 3 / h, traction speed is 60mm / min, and pause time is 2s.

[0127] Example 7

[0128] The method for preparing the aluminum-silicon alloy continuous casting rod billet provided in this embodiment is basically the same as that in Embodiment 1, except that in step (4), the elemental silicon feeding device extends into the aluminum liquid at a distance of 20 mm from the bottom.

[0129] Example 8

[0130] The method for preparing the aluminum-silicon alloy continuous casting rod blank provided in this embodiment comprises the following steps:

[0131] (1) Treatment of high-purity aluminum raw materials: 42% NaCl and 58% KCl were weighed as antioxidants in percentage by mass, and the mixture was ball-milled with anhydrous ethanol to form a paste, wherein the mass ratio of the antioxidant to the solvent was 3:7. The paste-like mixed material obtained after ball milling was applied to the surface of a high-purity aluminum block (Al content 99.999 wt.%), and then dried at 80° C. to form an antioxidant layer with a thickness of 0.5 mm, thereby obtaining treated metal aluminum.

[0132] (2) Preparation of a silicon feeding device: Block polycrystalline silicon (silicon content 99.9999 wt.%) is spread flat in the groove at the end of a graphite pressure rod, and a 70% by mass hexachloroethane ethanol solution (i.e., a refining agent solution) is filled between the block polycrystalline silicon, wherein the mass of the hexachloroethane ethanol solution accounts for 10% of the mass of the silicon. The block polycrystalline silicon is then dried at 40°C to obtain a silicon feeding device.

[0133] (3) High-purity aluminum melting: vertical continuous casting technology is used, and a graphite plug is used to plug the inlet end of the crystallizer. Then the induction power supply is started, and induction heating is performed until the treated metal aluminum is completely melted. The heating temperature is 900°C to obtain aluminum liquid.

[0134] (4) Aluminum-silicon fusion: The silicon feeding device is extended into the aluminum liquid to a position 15 mm from the bottom, and the graphite pressure rod of the silicon feeding device is rotated until no bubbles emerge from the liquid surface, thereby completing the smelting of the aluminum-silicon melt. The smelting temperature is 750°C.

[0135] (5) Degassing and impurity removal of the melt: Evacuate the aluminum silicon melt to a vacuum degree of 20Pa. Stop evacuating the aluminum silicon melt when no bubbles emerge. At the same time, open the argon valve to pass high-purity argon gas into the furnace and maintain a slight positive pressure in the furnace (0.115Mpa).

[0136] (6) Continuous casting: Start the crystallizer cooling water flow to 1.3m 3 / h, the dummy rod is inserted into the crystallizer and the graphite plug is lifted up. Under the action of buoyancy, the graphite plug floats on the surface of the melt, the traction mechanism is started and the traction speed is adjusted to 50mm / min, the pause time is 5s, and a continuous casting rod blank with a diameter of 7mm is obtained. The mass fraction of silicon in the continuous casting rod blank is 1%.

[0137] Example 9

[0138] The method for preparing the aluminum-silicon alloy continuous casting rod blank provided in this embodiment is substantially the same as that in Embodiment 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 rod billet provided in this comparative example is basically the same as that in Example 1, except that step (1) is not performed, and the treated metal aluminum in step (3) is replaced by a high-purity aluminum block (Al content 99.999wt.%) (the aluminum-silicon ratio is the same as in Example 1).

[0141] Comparative Example 2

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

[0143] Comparative Example 3

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

[0145] Comparative Example 4

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

[0147] Experimental example

[0148] The substrate tensile test refers to GB / T228.1-2010 "Tensile test of metallic materials Part 1: Room temperature test method". The continuous casting rod blanks of Example 1 and Comparative Examples 1 to Comparative Examples 4 are subjected to room temperature tensile tests at a speed of 5 mm / min using an MTS C45.105 microcomputer-controlled mechanical electronic universal testing machine. The tensile performance test results of the samples are the average value of 5 samples. The results of the aluminum-silicon alloy continuous casting rod blanks are shown in Table 1.

[0149] Table 1 Tensile properties test results

[0150]

[0151] Among them, excellent wire drawing performance is the characteristic mark of fine wire drawing. In order to compare the advantages and disadvantages of aluminum-silicon alloy continuous casting rod billets, the wire breakage rate index of the finished product can be used, that is, the average wire weight that can be drawn each time the wire breaks.

[0152] Figure 3 This is a metallographic picture of the cross section of the continuously cast rod blank prepared in Example 1. It can be seen that the aluminum-silicon alloy continuously cast rod blank has no inclusions and pores.

[0153] pass Figure 3 It can be seen from Table 1 that the aluminum-silicon alloy continuous casting rod blanks obtained after continuous casting of the aluminum-silicon melt prepared in each embodiment have no defects and inclusions, low pore content, uniform composition, stable structure, good plasticity, and good drawing properties.

[0154] However, in Comparative Example 1, no anti-oxidation substance was added, and the removal effect of aluminum oxide impurities was not as thorough as that in Example 1, and various drawing properties were poor.

[0155] Comparative Example 2 did not use a single-element silicon feeding device but directly added polysilicon. The degassing and impurity removal effect was not ideal compared with Example 1, and various drawing properties were poor.

[0156] In Comparative Example 3, unsuitable continuous casting parameters were used, and the precipitation of silicon with low solid solubility at room temperature caused segregation, resulting in poor drawing properties.

[0157] Comparative Example 4 uses only NaCl as an anti-oxidation substance, and its melting temperature is relatively high compared to the melting point of aluminum. Compared with Example 1, the covering effect is poor, resulting in a significant decrease in performance and poor various drawing properties.

[0158] In summary, the aluminum-silicon alloy continuous casting rod billet prepared by the preparation method of the aluminum-silicon alloy continuous casting rod billet provided by the present invention has no defects and inclusions, low pore content, and the aluminum-silicon alloy continuous casting rod billet has uniform composition, stable structure and good plasticity.

[0159] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, 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 invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing aluminum-silicon alloy continuous casting rod billet, characterized in that: The steps include: 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 the treated metal aluminum; the anti-oxidation substance includes NaCl and KCl; Placing elemental silicon in the groove at the end of the graphite pressure rod, and filling the space between the elemental silicon with a refining agent solution, and obtaining an elemental silicon feeding device after drying; After heating the treated metal aluminum to obtain aluminum liquid, extending the elemental silicon feeding device into the aluminum liquid so that the elemental silicon in the elemental silicon feeding device enters the aluminum liquid, and obtaining an aluminum silicon melt after smelting; After the aluminum-silicon melt is continuously cast, the aluminum-silicon alloy continuous casting rod blank is obtained.

2. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: The anti-oxidation substances include, by mass percentage, 40% to 45% NaCl, 50% to 55% KCl, 0% to 5% NaF, 0% to 5% Na3AlF6 and 0% to 5% CaF2.

3. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: At least one of the following conditions is met: (1) The gas pressure during continuous casting is a slightly positive pressure; (2) The flow rate of cooling water used in the continuous casting is 1 to 1.5 m 3 / h; (3) The continuous casting pulling speed is 40 to 60 mm / min; (4) The pause time of the continuous casting is 2 to 5 seconds; (5) Before the continuous casting, the vacuum is evacuated to a vacuum degree of 10 to 100 Pa, and then an inert gas is introduced to maintain the continuous casting gas pressure at a slightly positive pressure.

4. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: The vertical continuous casting technology is adopted, and the devices used for the smelting and the continuous casting include a graphite crucible, a crystallizer and a graphite plug; before the heating to melt the treated metal aluminum, the graphite plug is used to plug the inlet end of the crystallizer to achieve homogenization of the aluminum-silicon fusion; the graphite plug is opened when the continuous casting is carried out.

5. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: At least one of the following conditions is met: (1) The mass ratio of the antioxidant substance to the solvent is 2-3:7-8; (2) The solvent includes anhydrous ethanol; (3) The method for preparing the mixed material containing the antioxidant substance and the solvent comprises: mixing the antioxidant substance and the solvent and then ball milling; (4) The thickness of the anti-oxidation layer is 0.5 to 1 mm.

6. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: At least one of the following conditions is met: (1) The single-element silicon includes polycrystalline silicon; (2) the refining agent in the refining agent solution includes hexachloroethane; (3) The mass fraction of the refining agent in the refining agent solution is 60% to 80%; (4) The mass of the refining agent solution accounts for 5% to 20% of the mass of the elemental silicon.

7. The method for preparing the aluminum-silicon alloy continuous casting rod billet according to claim 1, characterized in that: At least one of the following conditions is met: (1) The heating temperature is 800-900° C.; (2) The elemental silicon feeding device extends to the end containing the elemental silicon and is 10 to 20 mm away from the bottom of the aluminum liquid; (3) During the smelting process, the elemental silicon feeding device is rotated; (4) The smelting temperature is 700-750°C.

8. Aluminum-silicon alloy continuous casting rod billet, characterized in that: The method for preparing an aluminum-silicon alloy continuous casting rod billet as claimed in any one of claims 1 to 7 is adopted; Preferably, the diameter of the aluminum-silicon alloy continuous casting rod blank is 4 to 8 mm; Preferably, the mass fraction of silicon element in the aluminum-silicon alloy continuous casting rod billet is 0.5% to 1.5%.

9. A bonding wire, characterized in that The aluminum-silicon alloy continuous casting rod billet is mainly prepared by the aluminum-silicon alloy continuous casting rod billet preparation method according to any one of claims 1 to 7, or the aluminum-silicon alloy continuous casting rod billet according to claim 8.

10. Use of the bonding wire as claimed in claim 9 in integrated circuits and semiconductor devices.

Images