Preparation method, application and preparation device of intermediate alloy

Abstract

The invention relates to the technical field of bonding wires, in particular to a preparation method, application and a preparation device of an intermediate alloy. The preparation method comprises the following steps: preparing materials; smelting is conducted, specifically, the raw materials are placed in a smelting container, a first protective atmosphere is adopted in the smelting container, the smelting container is placed in a second protective atmosphere, heating is conducted to enable the raw materials to be molten to obtain molten metal, the molten metal is subjected to swing mixing, and ultrasonic vibration is conducted after swing mixing is completed; and the bottom face of the smelting container is a plane, and in the smelting container, the thickness H of the molten metal and the area S of the bottom face of the smelting container meet the following relation that # imgabs0 # cooling is carried out, the bottom face of the smelting container is cooled under the ultrasonic vibration effect, and the molten metal is obtained after the molten metal is completely solidified. The intermediate alloy prepared through the method is good in uniformity and high in cleanliness.

Description

Technical Field

[0001] The present invention relates to the technical field of bonding wires, and in particular to a method for preparing an intermediate alloy and an application and a preparation device thereof. Background Art

[0002] Bonding wire is made by melting the main element and doping elements or alloying elements. In order to improve the composition accuracy and uniformity of bonding wire products, doping elements or alloying elements are usually prepared into binary master alloys with the main element. When melting the bonding wire, the master alloy is added to achieve the purpose of accurately adding doping elements or alloying elements. The characteristics of the master alloy of bonding wire are: small weight after one preparation; high-clean preparation, no impurities can be introduced; high material uniformity requirements, small composition errors of materials in various parts, which requires that various parts must be fully mixed and the organizational composition must be uniform to avoid component segregation and cause uneven element distribution.

[0003] At present, the preparation method of bonding wire master alloy is: doping elements and main elements are mixed according to the weight ratio, adding them into a vacuum induction melting furnace, heating them to above the melting point of the alloy under vacuum or inert gas protection, maintaining for a period of time, cooling them to room temperature and taking out the ingot. The master alloy produced by this method does not adopt homogenization means, the composition of each part is uneven, the composition accuracy error is large, and the cleanliness of the master alloy is low.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first purpose of the present invention is to provide a method for preparing an intermediate alloy to solve the technical problems existing in the prior art of uneven composition of various parts of the intermediate alloy, large composition accuracy error and low cleanliness; the method of the present invention adopts appropriate homogenization means, reasonably controls homogenization parameters, and adopts a double-layer protective atmosphere for protection, so that the intermediate alloy prepared has good uniformity and high cleanliness.

[0006] A second object of the present invention is to provide an application of the intermediate alloy prepared by the above-mentioned method for preparing the intermediate alloy in preparing bonding wires.

[0007] The third object of the present invention is to provide a device for preparing a master alloy, which is suitable for the method for preparing the master alloy as described above.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] A method for preparing a master alloy comprises the following steps:

[0010] S1. Ingredients are prepared according to the ingredient ratio;

[0011] S2. Melting, placing the prepared raw materials into a smelting container, wherein the interior of the smelting container adopts a first protective atmosphere, and the smelting container is placed in a second protective atmosphere, heating the raw materials to melt to obtain molten metal, and performing rocking mixing on the molten metal, and performing ultrasonic vibration after the rocking mixing is completed; the bottom surface of the smelting container is a plane, and in the smelting container, the thickness H of the molten metal and the bottom surface area S of the smelting container satisfy the following relationship: The unit of H is mm, and the unit of S is mm 2 , r is the coefficient of relationship between the bottom surface area and the thickness of the molten metal;

[0012] S3. Cooling: Cooling the bottom surface of the smelting container under the action of ultrasonic vibration, so that the molten metal is in a vertically distributed temperature field with heat on the top and cold on the bottom, forming a columnar crystal structure growing upward, and after the molten metal is completely solidified, the intermediate alloy is obtained.

[0013] The application of the master alloy prepared by the method for preparing the master alloy as described above in preparing bonding wires.

[0014] A preparation device for a master alloy comprises a vacuum chamber and a smelting container located in the vacuum chamber, a heating mechanism, a rotating mechanism, an ultrasonic vibration mechanism and a cooling mechanism;

[0015] The smelting container is used to contain raw materials required for preparing the master alloy, the bottom surface of the smelting container is a plane, and a protective atmosphere can be introduced into the interior of the smelting container;

[0016] The heating mechanism is used to heat the raw materials in the smelting container to form molten metal;

[0017] The rotating mechanism is drivingly connected to the smelting container so that the smelting container can rotate;

[0018] The ultrasonic vibration mechanism is connected to the smelting container and is used to apply ultrasonic vibration to the molten metal in the smelting container;

[0019] The cooling mechanism is movably disposed below the smelting container and is used to cool the bottom surface of the smelting container so that the molten metal in the smelting container solidifies in the form of columnar crystals to form the intermediate alloy.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The method of the present invention adopts a double-layer protective environment inside and outside the smelting container, which can prevent the intermediate alloy from being oxidized and ensure the cleanliness of the alloy. The intermediate alloy prepared by this method has a lower oxygen content and a higher cleanliness.

[0022] (2) The method of the present invention uses rocking mixing and ultrasonic vibration to fully mix the molten metal during the smelting process. The ultrasonic vibration can also completely expel the gas in the molten metal and make the molten metal flow completely to the bottom surface of the smelting container, so that the depth of the molten metal is uniform everywhere, and shrinkage is eliminated during the solidification process. The present invention can approximate the solidification plane to an infinite plane by reasonably controlling the relationship between the thickness H of the molten metal and the bottom surface area S of the smelting container. The horizontal direction has the same temperature field everywhere. The solidification stability field of the present invention can be approximately regarded as a vertical gradient temperature field on an infinite plane. The crystals in the solidification process grow from the low temperature zone (i.e., the lower part of the molten metal) to the high temperature zone (i.e., the upper part of the molten metal) into uniform columnar crystals. The intermediate alloy prepared by the method of the present invention has high uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 1 A process flow chart of a method for preparing a master alloy provided by an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of columnar crystal growth provided by an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the melting state of the master alloy melting device provided in an embodiment of the present invention;

[0027] Figure 4 A schematic diagram of the cooling state of the master alloy smelting device provided in an embodiment of the present invention;

[0028] Figure 5 A schematic diagram of a structure in which a quartz tube is used as a smelting container in an embodiment of the present invention.

[0029] Reference numerals:

[0030] 1-induction power supply; 2-induction coil; 3-smelting container; 4-seal; 5-rotating mechanism; 6-ultrasonic vibration table; 7-vacuum chamber; 8-cooling pool; 9-cooling medium; 10-elevator; 11-cooling machine; 12-molten metal; 13-vacuum system; 14-rotating seal; 15-temperature sensor; 16-inert gas source. DETAILED DESCRIPTION

[0031] 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.

[0032] like Figure 1 As shown, the first aspect of the present invention provides a method for preparing a master alloy, comprising the following steps:

[0033] S1. Ingredients are prepared according to the ingredient ratio;

[0034] S2. Melting, putting the prepared raw materials into a melting container, adopting a first protective atmosphere inside the melting container, and placing the melting container in a second protective atmosphere, heating the raw materials to melt to obtain molten metal, and performing reciprocating swing mixing on the molten metal to fully mix the molten metal. After the swing mixing, ultrasonic vibration is performed to completely discharge the gas in the molten metal, and the molten metal is completely flowed to the bottom surface of the melting container, so that the depth of the molten metal is uniform everywhere; the bottom surface of the melting container is a plane, and in the melting container, the thickness H of the molten metal and the bottom surface area S (inner surface area) of the melting container satisfy the following relationship: The unit of H is mm, and the unit of S is mm 2 , r is the coefficient of relationship between bottom area and molten metal thickness;

[0035] S3. Cooling. After smelting is completed, heating is stopped and the bottom of the smelting container is cooled under the action of ultrasonic vibration, so that the molten metal is in a vertically distributed temperature field with hot top and cold bottom, forming a columnar crystal structure growing upward. Ultrasonic energy can eliminate shrinkage during the solidification process. After the molten metal is completely solidified, the intermediate alloy is obtained.

[0036] The internal space of the smelting container of the present invention is a protective atmosphere, and the smelting container itself is also in an external environment containing a protective atmosphere. The double-layer protection measures can further reduce the oxygen content in the intermediate alloy and improve the cleanliness of the intermediate alloy. In addition, the present invention adopts reciprocating swing mixing and ultrasonic vibration homogenization means during the smelting process, which can fully mix the components in the molten metal and improve the structural uniformity of the intermediate alloy. Ultrasonic vibration is performed after the swing mixing is completed, which can completely discharge the gas in the molten metal and make the molten metal flow completely to the bottom surface of the smelting container, so that the depth of the molten metal is uniform everywhere; ultrasonic vibration can also eliminate shrinkage during the solidification process. By reasonably controlling the relationship between the bottom surface area S of the smelting container and the thickness H of the molten metal, the molten metal can be approximated as an infinitely large plane, so that the solidification stability field of the present invention can be approximately regarded as a vertical gradient temperature field on an infinitely large plane, and the crystals in the solidification process grow from the low temperature zone (i.e., the lower part of the molten metal) to the high temperature zone (i.e., the upper part of the molten metal) into uniform columnar crystals (such as Figure 2 The intermediate alloy prepared by the method of the present invention is in the shape of a sheet with uniform thickness, high cleanliness and good uniformity.

[0037] In some specific embodiments of the present invention, after step S3, the process further includes the steps of cutting and testing; wherein the cutting method is to place the intermediate alloy sheet obtained in step S3 horizontally and cut it into small pieces along the vertical direction. Since the structure of the intermediate alloy sheet along the horizontal directions is uniform, the intermediate alloy blocks cut by this method have high uniformity of composition.

[0038] In some specific embodiments of the present invention, the prepared master alloy may be any one of a silver-copper master alloy, a gold-beryllium master alloy, and a copper-palladium master alloy, but is not limited to these, and may also be other types of master alloys.

[0039] In some specific embodiments of the present invention, in step S1, the purity of the metal raw materials used is ≥99.99%, such as the purity of silver, copper, and palladium raw materials. Using high-purity raw materials can improve the cleanliness of the intermediate alloy product.

[0040] In some specific embodiments of the present invention, in step S1, the total mass of the raw materials is 50-500g, for example, it can be any point value among 50g, 100g, 200g, 300g, 400g, 500g or a range value consisting of any two point values.

[0041] In some specific embodiments of the present invention, in step S2, the first protective atmosphere and the second protective atmosphere are independently selected from a vacuum atmosphere or an inert gas atmosphere.

[0042] In some specific embodiments of the present invention, the first protective atmosphere is an inert gas atmosphere. Before smelting, the air inside the smelting container is evacuated to an absolute pressure of 10 -4 -10 -2 Pa, and then fill it with inert gas to atmospheric pressure; the second protective atmosphere is a vacuum atmosphere with an absolute pressure of 10 -1 -10Pa.

[0043] In some specific embodiments of the present invention, in step S2, the thickness H of the molten metal is 0.5-10 mm, for example, it can be any point value among 0.5 mm, 1.3 mm, 2.3 mm, 3 mm, 4 mm, 5.2 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a range value consisting of any two point values.

[0044] The thickness of the molten metal can be calculated by the following formula:

[0045]

[0046] Where, H is in mm; m is the weight of the smelted master alloy in g; ρ is the density of the master alloy in g / cm 3 ; S is the bottom surface area, unit is mm 2 .

[0047] The thickness H of the molten metal can be expressed as the mass m of each metal component. i and density ρ i The respective molten metal thicknesses are calculated and the total molten metal thickness is obtained by adding them together.

[0048] It can be seen from the above formula that H and S are inversely proportional. If H is too small, the bottom area of ​​the smelting container required for smelting will be too large, which will increase the cost. For smelting containers of certain materials (such as quartz tubes), the strength is difficult to guarantee. If H is too large, it will be difficult for columnar crystals to grow through the entire thickness, and the uniformity of the material will be reduced. Therefore, it is necessary to reasonably control the thickness H of the molten metal.

[0049] In some specific embodiments of the present invention, the bottom surface of the smelting container is rectangular in shape. In other embodiments, the bottom surface of the smelting container may be other shapes, such as circular, elliptical, etc.

[0050] In some specific embodiments of the present invention, in step S2, the swing angle of the reciprocating swing mixing is not less than 10°, for example, it can be any point value among ±12°, ±15°, ±20°, ±25°, ±30°, or a range value composed of any two point values; the maximum swing angle is based on ensuring that the detection head of the temperature sensor does not leave the liquid surface, the reciprocating swing mixing time is 5-20min, for example, it can be any point value among 5min, 8min, 10min, 12min, 15min, 18min, 20min, or a range value composed of any two point values; the reciprocating swing speed is 10-300rpm, for example, it can be any point value among 10rpm, 15rpm, 30rpm, 60rpm, 100rpm, 150rpm, 200rpm, 300rpm, or a range value composed of any two point values; the reciprocating swing can fully mix the molten metal and improve the uniformity of the intermediate alloy.

[0051] In some specific embodiments of the present invention, in steps S2 and S3, the frequency f of the ultrasonic vibration satisfies the following relationship:

[0052]

[0053] Where, the unit of f is Hz; l 晶 is the unit cell parameter of the metal, in mm; R is the continuous growth rate of the crystal, in mm / s; μ1 is a constant related to the diffusion coefficient and latent heat of crystallization, in mm / (s·K), and is taken as 100; △T k is the kinetic undercooling of the interface front, in K, and is taken as 10 -4 K; n is the number of ultrasonic vibrations of each unit cell during crystal solidification, n ≥ 1.

[0054] If it can be ensured that the molten metal vibrates at least once during the solidification of each unit cell, the molten metal can be filled into the gaps caused by solidification shrinkage, avoiding shrinkage on the upper surface of the master alloy and making the structure of each part of the master alloy very uniform. When n is 1, the calculated frequency is the minimum frequency. When the frequency is lower than this value, shrinkage cavities will form on the upper part of the metal during solidification, and the distribution along the plane direction will be uneven.

[0055] In some specific embodiments of the present invention, in steps S2 and S3, the power P of the ultrasonic vibration satisfies the following relationship:

[0056]

[0057] Among them, P is in kW; M is the total weight installed on the ultrasonic vibration table, in kg; A is the ultrasonic amplitude, in m, generally 10 -6 m; f is the ultrasonic frequency, the unit is Hz.

[0058] When the ultrasonic power is lower than this value, the metal will not vibrate sufficiently during the solidification process, and the composition deviation and unevenness of the produced intermediate alloy will increase.

[0059] In some specific embodiments of the present invention, in step S2, the ultrasonic vibration time is 1-20 minutes, for example, it can be any point value of 1 minute, 3 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, or a range value consisting of any two point values. This ultrasonic vibration step can not only mix the molten metal evenly, but also discharge the gas in the molten metal, so that the molten metal flows to the bottom surface of the smelting container to form a molten metal with uniform thickness.

[0060] In some specific embodiments of the present invention, in step S3, the cooling temperature is 5-30°C, for example, it can be any point value among 5°C, 10°C, 15°C, 20°C, 25°C, 30°C or a range value consisting of any two point values.

[0061] A second aspect of the present invention provides a use of an intermediate alloy prepared by the method for preparing an intermediate alloy according to any one of the aforementioned embodiments in preparing a bonding wire.

[0062] like Figure 3 and Figure 4 As shown, the third aspect of the present invention provides a device for preparing a master alloy, which is applicable to the method for preparing a master alloy described in any one of the aforementioned embodiments, and comprises a vacuum chamber 7 and a smelting container 3 located in the vacuum chamber 7, a heating mechanism, a rotating mechanism 5, an ultrasonic vibration mechanism and a cooling mechanism;

[0063] The smelting container 3 is used to contain the raw materials required for preparing the master alloy. The bottom surface of the smelting container 3 is a plane, in order to ensure that the thickness of the molten metal is uniform everywhere. The interior of the smelting container 3 can be isolated from the vacuum chamber 7 during operation, and a protective atmosphere can be introduced into the interior. The smelting container 3 and the vacuum chamber 7 can form a double-layer protective environment for the metal during smelting.

[0064] The heating mechanism is used to heat the raw materials in the smelting container 3 to form molten metal;

[0065] The rotating mechanism 5 is drivingly connected to the smelting container 3 so that the smelting container 3 can rotate to mix the molten metal;

[0066] The ultrasonic vibration mechanism is connected to the smelting container 3 and is used to apply ultrasonic vibration to the molten metal in the smelting container 3. The ultrasonic vibration is used to fully mix the molten metal and completely discharge the gas inside the molten metal. During cooling, the ultrasonic vibration can also eliminate shrinkage.

[0067] The cooling mechanism is movably disposed below the smelting container 3 and is used to cool the bottom surface of the smelting container 3 so that the molten metal in the smelting container 3 solidifies in a uniform columnar crystal form to form an intermediate alloy.

[0068] In some specific embodiments of the present invention, the ultrasonic vibration mechanism includes an ultrasonic vibration table 6 with an ultrasonic generator, the rotating mechanism 5 is installed on the ultrasonic vibration table 6, one end of the smelting container 3 is connected to the rotating mechanism 5, and the other end of the smelting container 3 is connected to the vacuum system 13 and the inert gas source 16 through the rotating seal 14. The vacuum system 13 and the inert gas source 16 are used to provide a first protective atmosphere inside the smelting container 3, and the vacuum chamber 7 is used to provide a second protective atmosphere for the outside of the smelting container, thereby providing double-layer protection for the smelted metal and improving the cleanliness of the master alloy.

[0069] In some specific embodiments of the present invention, the working process of the above-mentioned preparation device is as follows: the smelting container 3 filled with raw materials is installed with the rotating mechanism 5, the smelting container 3 is connected to the vacuum system 13 and the inert gas source 16 by rotating the seal 14, the air in the smelting container 3 and the vacuum chamber 7 is extracted, and the smelting container 3 is filled with inert gas, wherein the vacuum chamber 7 can be connected to the vacuum system 13 through a pipeline and a valve to extract the air therein, or other vacuum systems can be used to evacuate it separately, and the smelting mechanism is arranged in the vacuum chamber 7, which can provide a double-layer protective environment for smelting to prevent the intermediate alloy from The raw materials are heated and melted to obtain the molten metal 12. The rotating mechanism 5 is started to drive the smelting container 3 to rotate and swing back and forth to fully mix the molten metal 12. After a period of rotation and swinging, the rotating mechanism 5 is stopped, and the ultrasonic vibration is turned on to make the molten metal in the smelting container 3 be in the ultrasonic vibration, and the gas in the molten metal 12 is completely discharged, and the molten metal 12 is completely flowed to the bottom surface of the smelting container 3, and the depth of the molten metal in each place is made uniform. The heating is stopped, and the cooling mechanism is started to cool the bottom surface of the smelting container 3, and the molten metal solidifies to form uniform columnar crystals.

[0070] In some specific embodiments of the present invention, the heating mechanism comprises an induction coil 2 located outside the smelting container 3 , and the induction coil 2 is controlled by an induction power supply 1 .

[0071] In some specific embodiments of the present invention, the cooling mechanism includes a cooling pool 8 and an elevator 10 arranged at the bottom of the cooling pool 8. The cooling pool 8 is used to accommodate a cooling medium 9. The cooling pool 8 is connected to the inlet and outlet of a cooler 11 through a pipeline for cooling the cooling medium 9.

[0072] like Figure 4As shown, after smelting is completed, heating is stopped, the induction coil 2 is moved aside, the elevator 10 is started, the cooling pool 8 is raised, and the bottom surface of the smelting container 3 is immersed in the cooling medium. The molten metal is in a vertically distributed uniform temperature field with heat on the top and cold on the bottom, and a uniform columnar crystal structure growing upward is formed in the ultrasonic vibration. The cooling medium 9 is cooled by the cooler 11.

[0073] In some specific embodiments of the present invention, the cooling medium 9 used may be cooling water.

[0074] In some specific embodiments of the present invention, a temperature sensor 15 is provided in the smelting container 3 for detecting the temperature of the molten metal 12 .

[0075] like Figure 5 As shown, in some specific embodiments of the present invention, the smelting container 3 can be a quartz tube, and its structure includes a quartz tube body and inlet tubes located at both ends of the quartz tube body, and the two inlet tubes are coaxially arranged with the quartz tube, wherein the inlet tube at one end is connected to the vacuum system 13 and the inert gas source 16 through a rotating seal 14, and the inlet tube at the other end is connected to the rotating mechanism 5 through a seal 4. In other embodiments, the smelting container 3 can also be a container made of other high-temperature resistant materials.

[0076] The following describes some embodiments of the present invention in detail in conjunction with specific application examples. The raw materials used in the examples can be purchased from the market unless otherwise specified. The following examples are all implemented using the master alloy preparation device provided by the present invention.

[0077] Example 1

[0078] S1. Ingredients: weigh 49g (M) silver particles with a purity of 99.999% Ag ) and 1g of copper particles with a purity of 99.99% (M Cu ), obtain raw materials;

[0079] S2. Melting: put the prepared raw materials into the quartz tube. After the quartz tube is installed and ensured to be reliably sealed, the air in the quartz tube and the vacuum chamber is extracted to make the absolute pressure in the quartz tube reach 1×10 -3 Pa, the absolute pressure in the vacuum chamber is 1×10 -1 Pa, then fill the quartz tube with argon to atmospheric pressure, turn on the induction power supply, use the induction coil for heating, melt the raw materials to obtain molten metal, start the rotating mechanism for reciprocating swing mixing, the swing angle is ±12°, the swing speed is 30rpm, the swing mixing is 20min, the rotating mechanism is stopped, the ultrasonic vibration is turned on, the gas in the molten metal is discharged, the molten metal is completely flowed to the bottom surface of the quartz tube, and the depth of the molten metal is uniform everywhere, and the heating is stopped after 10min of ultrasonic vibration;

[0080] The dimensions of the quartz tube used in this embodiment are 50 mm in height, 50 mm in bottom length L, 50 mm in bottom width W, 2 mm in wall thickness, and 10 mm inlet diameter; the thickness of the molten metal is calculated as:

[0081]

[0082] Relative to the molten metal, the bottom surface of the quartz tube can be regarded as an infinite plane;

[0083] Calculate the ultrasonic frequency as:

[0084]

[0085] In this embodiment, the ultrasonic frequency is selected to be 28kHz;

[0086] The rotating mechanism uses a motor + reducer, weighing 500g, the quartz tube weighs 100g, the seal weighs 100g, the molten metal weighs 50g, and the total weight M on the ultrasonic vibration table is: 0.75kg;

[0087] Calculate the ultrasonic frequency:

[0088]

[0089] In this embodiment, the ultrasonic power is selected to be 4.5kW;

[0090] S3. Cooling, moving the heating coil aside, raising the cooling pool, immersing the bottom of the quartz tube in cooling water, the molten metal is in a vertically distributed uniform temperature field with heat on top and cold on the bottom, and forms a uniform columnar crystal structure that grows upward in the ultrasonic vibration;

[0091] S4. Break the quartz tube to remove the alloy sheet and cut it into pieces. Place the intermediate alloy sheet horizontally and cut it into small pieces vertically.

[0092] S5. Randomly select 5 blocks from the cut blocks, use ICP to detect the Cu content in the master alloy, and test its oxygen content. The test results are shown in Table 1.

[0093] Example 2

[0094] S1. Ingredients: weigh 99g (M) gold flakes with a purity of 99.999% Au ) and 1g of beryllium particles with a purity of 99.99% (M Be ), obtain raw materials;

[0095] S2. Melting: put the prepared raw materials into the quartz tube. After the quartz tube is installed and ensured to be reliably sealed, the air in the quartz tube and the vacuum chamber is extracted to make the absolute pressure in the quartz tube reach 1×10-2 Pa, the absolute pressure in the vacuum chamber is 10Pa, and then argon is filled into the quartz tube to atmospheric pressure, the induction power supply is turned on, and the induction coil is used for heating to melt the raw materials to obtain molten metal, and the rotating mechanism is started for reciprocating swing mixing, the swing angle is ±15°, the swing speed is 60rpm, and the swing mixing is 10min, the rotating mechanism is stopped, and the ultrasonic vibration is turned on to discharge the gas in the molten metal, so that the molten metal flows completely to the bottom surface of the quartz tube, and the depth of the molten metal is uniform everywhere, and the heating is stopped after 10min of ultrasonic vibration;

[0096] The dimensions of the quartz tube used in this embodiment are 50 mm in height, 70 mm in bottom length L, 70 mm in bottom width W, 2 mm in wall thickness, and 15 mm inlet diameter; the thickness of the molten metal is calculated as:

[0097]

[0098] Relative to the molten metal, the bottom surface of the quartz tube can be regarded as an infinite plane;

[0099] Calculate the ultrasonic frequency as:

[0100]

[0101] In this embodiment, the ultrasonic frequency is selected to be 25kHz;

[0102] The rotating mechanism uses a swing cylinder, which weighs 270g, the quartz tube weighs 120g, the seal weighs 150g, the molten metal weighs 100g, and the total weight M on the ultrasonic vibration table is: 0.64kg;

[0103] Calculate the ultrasonic frequency:

[0104]

[0105] In this embodiment, the ultrasonic power is selected to be 2.5kW;

[0106] S3. Cooling, moving the heating coil aside, raising the cooling pool, immersing the bottom of the quartz tube in cooling water, the molten metal is in a vertically distributed uniform temperature field with heat on top and cold on the bottom, and forms a uniform columnar crystal structure that grows upward in the ultrasonic vibration;

[0107] S4. Break the quartz tube to remove the alloy sheet and cut it into pieces. Place the intermediate alloy sheet horizontally and cut it into small pieces vertically.

[0108] S5. Randomly select 5 blocks from the cut blocks, use ICP to detect the Be content in the master alloy, and test its oxygen content. The test results are shown in Table 2.

[0109] Example 3

[0110] S1. Ingredients: weigh 490 g (M) of copper ingot with a purity of 99.999% Cu ) and 10 g of palladium powder with a purity of 99.99% (M Pd ), breaking the copper ingot into small copper blocks to obtain raw materials;

[0111] S2. Melting: put the prepared raw materials into the quartz tube. After the quartz tube is installed and ensured to be reliably sealed, the air in the quartz tube and the vacuum chamber is extracted to make the absolute pressure in the quartz tube reach 8×10 -3 Pa, the absolute pressure in the vacuum chamber is 5Pa, and then argon is filled into the quartz tube to atmospheric pressure, the induction power supply is turned on, and the induction coil is used for heating to melt the raw materials to obtain molten metal, and the rotating mechanism is started for reciprocating swing mixing, the swing angle is ±20°, the swing speed is 15rpm, and the swing mixing is 5min. The rotating mechanism is stopped, and the ultrasonic vibration is turned on to discharge the gas in the molten metal, so that the molten metal flows completely to the bottom surface of the quartz tube, and the depth of the molten metal is uniform everywhere, and the heating is stopped after 10min of ultrasonic vibration;

[0112] The dimensions of the quartz tube used in this embodiment are 50 mm in height, 120 mm in bottom length, 100 mm in bottom width, 3 mm in wall thickness, and 20 mm inlet diameter; the thickness of the molten metal is calculated as:

[0113]

[0114] Relative to the molten metal, the bottom surface of the quartz tube can be regarded as an infinite plane;

[0115] Calculate the ultrasonic frequency as:

[0116]

[0117] In this embodiment, the ultrasonic frequency is selected to be 28kHz;

[0118] The rotating mechanism uses a motor plus a connecting rod mechanism, which weighs 1000g, the quartz tube weighs 350g, the seal weighs 200g, the metal melt weighs 500g, and the total weight M on the ultrasonic vibration table is: 2.05kg;

[0119] Calculate the ultrasonic frequency:

[0120]

[0121] In this embodiment, the ultrasonic power is selected to be 12kW;

[0122] S3. Cooling, moving the heating coil aside, raising the cooling pool, immersing the bottom of the quartz tube in cooling water, the molten metal is in a vertically distributed uniform temperature field with heat on top and cold on the bottom, and forms a uniform columnar crystal structure that grows upward in the ultrasonic vibration;

[0123] S4. Break the quartz tube to remove the alloy sheet and cut it into pieces. Place the intermediate alloy sheet horizontally and cut it into small pieces vertically.

[0124] S5. Randomly select 5 blocks from the cut blocks, use ICP to detect the Pd content in the master alloy, and test its oxygen content. The test results are shown in Table 3.

[0125] Comparative Example 1

[0126] S1. Ingredients: weigh 49g (M) silver particles with a purity of 99.999% Ag ) and 1g of copper particles with a purity of 99.99% (M Cu ), obtain raw materials;

[0127] S2. Melting: Put the raw materials into a high-purity graphite crucible, put the crucible into a vacuum induction melting furnace for melting, and extract the air in the melting furnace to make the absolute pressure inside reach 3×10 -3 Pa, filled with argon protection, and smelting was carried out. Electromagnetic stirring was added during the smelting process, the stirring frequency was 15 Hz, and the stirring was carried out for 10 minutes.

[0128] S3. Detection: Materials were taken from 5 different locations on the refined master alloy ingot, and the copper content in the master alloy was detected by ICP, and its oxygen content was tested. The test results are shown in Table 1.

[0129] Comparative Example 2

[0130] Comparative Example 2 is similar to Example 1, except that the ultrasonic frequency is 15 kHz, and the other conditions are the same as those of Example 1. The composition and oxygen content of the intermediate alloy are measured, and the results are shown in Table 1.

[0131] Comparative Example 3

[0132] Comparative Example 3 is similar to Example 2, except that the ultrasonic power is 1 kW, and the other conditions are the same as those of Example 2. The composition and oxygen content of the intermediate alloy are measured, and the results are shown in Table 2.

[0133] Comparative Example 4

[0134] Comparative Example 4 is similar to Example 3, except that: the bottom length of the quartz tube is L=70 mm, the bottom width is W=70 mm, the height is 50 mm, the wall thickness is d=3 mm, the calculated metal liquid thickness is H=13.6 mm, r=4.7, and the other conditions are the same as those in Example 3. The composition and oxygen content of the intermediate alloy are measured, and the results are shown in Table 3.

[0135] Test example

[0136] (1) The copper content and oxygen content of different blocks or different positions of the master alloys obtained in Example 1, Comparative Example 1 and Comparative Example 2 were tested respectively. The results are shown in Table 1;

[0137] (2) The beryllium content and oxygen content of different blocks or different positions of the master alloys obtained in Example 2 and Comparative Example 3 were tested respectively. The results are shown in Table 2;

[0138] (3) The palladium content and oxygen content of different blocks or different positions of the master alloys obtained in Example 3 and Comparative Example 4 were tested respectively. The results are shown in Table 3;

[0139] In the test example, the component deviation is calculated using the root mean square error method; the non-uniformity is calculated using the formula: (maximum value - minimum value) / theoretical value.

[0140] Table 1

[0141]

[0142] By comparing Example 1 with Comparative Example 1, it can be seen that the composition deviation and unevenness of the master alloy obtained by the ordinary vacuum melting method are greater than the composition deviation and unevenness of the master alloy obtained by the method of the present invention. At the same time, because Comparative Example 1 only uses one layer of vacuum system, although the vacuum melting furnace has been evacuated to an absolute pressure of 3×10 -3 Pa, but because there is no protection of the outer vacuum system, during the smelting process, the vacuum system is in a closed state, and the oxygen in the air will gradually penetrate slowly into the furnace, so the oxygen content of the obtained intermediate alloy is higher than that of the intermediate alloy obtained by the present invention.

[0143] The ultrasonic frequency of Comparative Example 2 is lower than that of Example 1, n<1, the metal does not vibrate sufficiently during the solidification process, and it cannot satisfy that the molten metal vibrates at least once when each unit cell solidifies. The composition deviation and unevenness of the prepared intermediate alloy are higher than those of Example 1, but still better than the intermediate alloy produced by ordinary vacuum melting.

[0144] Table 2

[0145]

[0146]

[0147] The ultrasonic power of Comparative Example 3 is lower than that of Example 2. The metal was not sufficiently vibrated during the solidification process, and the composition deviation and non-uniformity of the prepared intermediate alloy were higher than those in Example 2.

[0148] Table 3

[0149]

[0150] The bottom surface area of ​​the quartz tube in Comparative Example 4 is smaller than that in Example 3. The bottom surface of the molten metal solidification cannot be regarded as an infinite plane. The metal liquid level is relatively high and cannot grow into uniform columnar crystals. The structures of various parts are uneven after solidification. The composition deviation and unevenness of the prepared intermediate alloy are higher than those in Example 3.

[0151] 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 a master alloy, characterized in that: The following steps are involved: S1. Ingredients are prepared according to the ingredient ratio; S2. Melting, placing the prepared raw materials into a smelting container, wherein the interior of the smelting container adopts a first protective atmosphere, and the smelting container is placed in a second protective atmosphere, heating the raw materials to melt to obtain molten metal, and performing rocking mixing on the molten metal, and performing ultrasonic vibration after the rocking mixing is completed; the bottom surface of the smelting container is a plane, and in the smelting container, the thickness H of the molten metal and the bottom surface area S of the smelting container satisfy the following relationship: r is the coefficient of relationship between the bottom surface area and the thickness of the molten metal; S3. Cooling: Cooling the bottom surface of the smelting container under the action of ultrasonic vibration, so that the molten metal is in a vertically distributed temperature field with heat on the top and cold on the bottom, forming a columnar crystal structure growing upward, and after the molten metal is completely solidified, the intermediate alloy is obtained.

2. The method for preparing the master alloy according to claim 1, characterized in that: In step S2, the first protective atmosphere and the second protective atmosphere are independently selected from a vacuum atmosphere or an inert gas atmosphere.

3. The method for preparing the master alloy according to claim 1, characterized in that: In step S2, the thickness H of the molten metal is 0.5-10 mm; And / or, the swing angle of the swing mixing is not less than 10°, the swing mixing time is 5-20 min, and the swing mixing speed is 10-300 rpm.

4. The method for preparing the master alloy according to claim 1, characterized in that: In steps S2 and S3, the frequency f of the ultrasonic vibration satisfies the following relationship: Among them, l 晶 is the unit cell parameter of the metal; R is the continuous growth rate of the crystal; μ1 is a constant related to the diffusion coefficient and latent heat of crystallization; △T k is the kinetic undercooling at the interface front; n is the number of ultrasonic vibrations of each unit cell during crystal solidification, n ≥ 1.

5. The method for preparing the master alloy according to claim 1, characterized in that: In steps S2 and S3, the power P of the ultrasonic vibration satisfies the following relationship: Where, M is the total weight installed on the ultrasonic vibration table; A is the ultrasonic amplitude; and f is the ultrasonic frequency.

6. The method for preparing the master alloy according to claim 1, characterized in that: In step S2, the ultrasonic vibration time is 1-20 minutes.

7. The method for preparing the master alloy according to claim 1, characterized in that: In step S3, the cooling temperature is 5-30°C.

8. Use of the master alloy prepared by the method for preparing the master alloy according to any one of claims 1 to 7 in preparing bonding wires.

9. A device for preparing a master alloy, characterized in that: A method for preparing the master alloy according to any one of claims 1 to 7, comprising a vacuum chamber and a smelting container located in the vacuum chamber, a heating mechanism, a rotating mechanism, an ultrasonic vibration mechanism and a cooling mechanism; The smelting container is used to contain raw materials required for preparing the master alloy, the bottom surface of the smelting container is a plane, and a protective atmosphere can be introduced into the interior of the smelting container; The heating mechanism is used to heat the raw materials in the smelting container to form molten metal; The rotating mechanism is drivingly connected to the smelting container so that the smelting container can rotate; The ultrasonic vibration mechanism is connected to the smelting container and is used to apply ultrasonic vibration to the molten metal in the smelting container; The cooling mechanism is movably disposed below the smelting container and is used to cool the bottom surface of the smelting container so that the molten metal in the smelting container solidifies in the form of columnar crystals to form the intermediate alloy.

10. The device for preparing the master alloy according to claim 9, characterized in that: Contains at least one of the following characteristics: (1) The ultrasonic vibration mechanism comprises an ultrasonic vibration table with an ultrasonic generator, the rotating mechanism is mounted on the ultrasonic vibration table, one end of the smelting container is connected to the rotating mechanism, and the other end of the smelting container is connected to a vacuum system and an inert gas source through a rotating seal; (2) the heating mechanism comprises an induction coil located outside the smelting vessel, and the induction coil is controlled by an induction power supply; (3) The cooling mechanism includes a cooling pool and a lift arranged at the bottom of the cooling pool. A cooling medium is arranged in the cooling pool. The cooling pool is connected to the inlet and outlet of the cooling machine.

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