SnSb alloy pre-forming soft solder and preparation method thereof

Abstract

The invention relates to SnSb alloy preformed soft solder and a preparation method thereof, and belongs to the field of welding materials. The preparation method of the SnSb alloy pre-forming soft solder comprises the following steps: (1) preparing materials: preparing metal tin and metal antimony into an alloy raw material; (2) alloy smelting: smelting the alloy raw materials into a melt and preserving heat; wherein the smelting temperature is 800 to 950 DEG C; (3) ultrasonic treatment: carrying out ultrasonic treatment on the melt; wherein the ultrasonic power is not lower than 1KW, the ultrasonic frequency is not lower than 20KHz, and the ultrasonic treatment time is not shorter than 1min; (4) high-temperature casting is conducted, specifically, the melt obtained after ultrasonic treatment is cast, and the casting temperature is 800-950 DEG C; (5) water-cooling forming; and the SnSb alloy pre-forming soft solder is obtained. The SnSb alloy preformed soft solder is prepared by introducing ultrasonic treatment and combining a high-temperature casting and water-cooling forming method, intermetallic compounds can be effectively refined, and the intermetallic compounds of the prepared SnSb alloy preformed soft solder are small in size and uniform in distribution.

Description

Technical Field

[0001] The invention relates to the field of welding materials for electronic component packaging, and in particular to a SnSb alloy preformed soft solder and a preparation method thereof. Background Art

[0002] SnSb lead-free solder is widely used in the field of electronic packaging because of its good wettability, low melting point welding characteristics and cost advantage over other lead-free solders.

[0003] With the promotion of welding technology, although SnSb alloy has broad application prospects in the field of welding, SnSb alloy with an antimony content of 10-12% by weight will inevitably produce brittle intermetallic compounds (precipitation phases) during the casting process. Such intermetallic compounds are coarse and have poor forming ability, and are prone to fall off during the forming process. SnSb alloy is often processed into strips with a thickness of no more than 60μm. Due to the above reasons, the strips are prone to unevenness, breakage and other problems, affecting the reliability of SnSb alloy as solder.

[0004] Therefore, it is necessary to conduct further research on the microstructure refinement process to address the problem of coarse intermetallic compounds in existing SnSb alloys. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a SnSb alloy preformed solder and a preparation method thereof. The present invention introduces ultrasonic treatment and combines high temperature casting and water cooling molding to prepare the SnSb alloy preformed solder, which can effectively refine the intermetallic compounds of the SnSb alloy preformed solder, so that the prepared SnSb alloy preformed solder has small intermetallic compounds and uniform distribution. The preparation method of the present invention is close to industrial production practice, simple to operate, and easy to realize mass production of the product.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a SnSb alloy preformed solder, characterized in that it comprises the following steps:

[0008] (1) Batching: preparing metallic tin and metallic antimony into alloy raw materials;

[0009] (2) Alloy smelting: melting the alloy raw materials into a melt and keeping it warm; the smelting temperature is 800-950°C;

[0010] (3) Ultrasonic treatment: ultrasonic treatment of the melt; wherein the ultrasonic power is not less than 1 kW, the ultrasonic frequency is not less than 20 kHz, and the ultrasonic treatment time is not less than 1 min;

[0011] (4) High temperature casting: Casting the ultrasonically treated melt at a casting temperature of 800-950°C;

[0012] (5) Water cooling forming;

[0013] The SnSb alloy preformed solder is obtained.

[0014] The SnSb alloy preformed solder preparation method of the present invention prepares the SnSb alloy preformed solder by introducing ultrasonic treatment combined with high-temperature casting and water-cooling molding, which can effectively refine intermetallic compounds and produce SnSb alloy preformed solder with an intermetallic compound size of ≤60μm, thereby solving the problem of coarse intermetallic compounds of SnSb alloy prepared by the existing method and improving the reliability of the SnSb alloy preformed solder used as solder.

[0015] The present invention introduces ultrasonic treatment during the smelting process, and limits the ultrasonic power to not less than 1KW, the ultrasonic frequency to not less than 20KHz, and the ultrasonic treatment time to not less than 1min. The above ultrasonic treatment can change the characteristics of the metal solidification process, refine the structure, reduce component segregation, improve mechanical properties, etc.; the cavitation effect and acoustic streaming effect generated by the ultrasonic wave refine the grains of the SnSb alloy, and the cavitation bubble will generate a strong shock wave at the moment of closing, breaking the coarse grains in the molten metal, refining the solidification structure of the metal, and under the action of the acoustic flow, making the composition of the SnSb alloy melt more uniform. If the ultrasonic power is too low or the ultrasonic frequency is too low or the ultrasonic treatment time is too short during the ultrasonic treatment, the cavitation effect and acoustic streaming effect are weak, and the size of the intermetallic compound of the manufactured SnSb alloy preformed solder is too large.

[0016] The present invention performs high-temperature casting of the ultrasonically treated melt at 800-950°C, and high-temperature casting is beneficial to achieve melt structure transformation. The present invention uses high-temperature smelting and high-temperature casting, that is, melt superheating treatment: the liquid SnSb alloy is superheated to 800-950°C and kept warm, and the cooling rate is controlled after reaching a stable state, so that the excellent structure of the high-temperature melt can be retained to a low temperature, thereby improving the solid structure. It is easy for those skilled in the art to know that the melt is composed of disordered bands of solid-like atomic groups with different compositions and structures and various component atoms between them in a disordered distribution. When the melt temperature is low, the atomic arrangement and bonding inside the solid-like atomic clusters are similar to the original solid, that is, the alloy has a large amount of solid residual solid-like short-range ordered structure in the temperature range not high above the melting point; therefore, for alloy melts with lower temperatures, there is microscopic inhomogeneity. The present invention melts the SnSb alloy at a melting temperature of 800-950°C and casts it at a casting temperature of 800-950°C, which is beneficial to the transformation of the melt structure. On the one hand, a large number of solid-like atomic clusters in the melt are broken, and the melt structure becomes more uniform and disordered, so the nucleation rate of the SnSb alloy melt is improved and the solidification structure is refined during crystallization; on the other hand, after the melt structure is transformed, the atomic clusters in the melt are transformed into solid-like atomic clusters different from those during low-temperature melting, which increases the additional interface free energy in the nucleation process, resulting in an increase in the critical free energy required for nucleation, and the nucleation rate is improved during alloy solidification, but the grain growth becomes difficult, so the structure is fine and uniform. The present invention controls the casting temperature to 800-950°C. If the casting temperature is too low, the size of the intermetallic compound of the manufactured SnSb alloy preformed solder is too large; if the casting temperature is too high, the manufactured SnSb alloy preformed solder will be easily oxidized, overburned, shrinkage cavity and looseness will occur.

[0017] The present invention can effectively improve the cooling rate of the ingot by adopting a water-cooling forming method, and increase the supercooling degree and nucleation rate of the SnSb alloy. The present invention adopts a water-cooling forming method to increase the supercooling degree of the cast melt, thereby having the following effects on the SnSb alloy structure: (1) reducing or stabilizing the size of the intermetallic compound and increasing the number of precipitated phases; (2) refining the dendrites and reducing the distance between the dendrites by 10-15%; (3) making the alloying elements more uniform and reducing segregation.

[0018] As a preferred solution, in step (1), the weight content of metal antimony in the alloy raw material is 10-12%. In the present invention, in step (1), metal tin and metal antimony are configured into alloy raw materials. In addition to configuring them into alloy raw materials with the above-mentioned mass percentage content, the mass percentages of the two metals in the SnSb alloy currently available in the art can also be used to configure them, so that the metal tin and the metal antimony are configured in an appropriate mass percentage, so as to form a SnSb alloy preformed soft solder.

[0019] Preferably, the metallic tin is a high-purity Sn bar, and the metallic antimony is a high-purity Sb block.

[0020] As a preferred solution, in step (2), a resistance furnace is used for smelting. The resistance furnace can meet the requirement of heating the smelting temperature to 800-950°C, but the present invention is not limited to the use of a resistance furnace for smelting. Other commonly used smelting furnace equipment in the field is also applicable for smelting, as long as the smelting temperature is 800-950°C. During smelting, the present invention controls the smelting temperature at 800-950°C to keep the liquid SnSb alloy superheated to a high temperature of 800-950°C, that is, to keep the liquid SnSb alloy superheated to a higher temperature above the melting point of the SnSb alloy, thereby creating conditions for subsequent steps.

[0021] As a preferred solution, in step (2), the holding time is 20-40 minutes. During the smelting process, the melt holding time is controlled to be 20-40 minutes so that the melt reaches a high temperature stable state and the high temperature melt has a stable and excellent structure. More preferably, the holding time is 30 minutes (i.e. 0.5 hours).

[0022] As a preferred solution, in step (2), after the melt is kept warm, stirred, and deslagging, step (3) is then carried out, i.e., ultrasonic treatment is introduced again.

[0023] As a preferred solution, in step (3), the ultrasonic power is preferably 1-3KW, specifically 1KW, 2KW, 3KW, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; the ultrasonic frequency is preferably 20-23KHz, specifically 20KHz, 21KHz, 22KHz, 23KHz, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; the ultrasonic treatment time is preferably 1-5min, specifically 1min, 2min, 3min, 4min, 5min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; more preferably, the ultrasonic treatment time is 2-3min. In addition, the above-mentioned ultrasonic power, ultrasonic frequency, and ultrasonic treatment time range do not represent limitations on the present invention, and the values ​​exceeding the corresponding range are also applicable, and the ultrasonic power is not less than 1KW, the ultrasonic frequency is not less than 20KHz, and the ultrasonic treatment time is not less than 1min, so as to ensure that the melt can be fully ultrasonically treated. However, too high ultrasonic power, too high ultrasonic frequency, and too long ultrasonic treatment time will not further play a role in refinement, but will consume energy and increase costs. Therefore, the above range is preferred.

[0024] As a preferred solution, in step (3), the ultrasonic treatment is carried out from the top, and the ultrasonic probe is inserted into the melt from the top by 1-5 cm, specifically 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. More preferably, the ultrasonic probe is inserted into the melt by 2-3 cm.

[0025] As a preferred solution, in step (4), a semi-cylindrical copper mold is used for casting. The thermal conductivity of the semi-cylindrical copper casting mold selected is better than that of the traditional graphite mold, so as to facilitate water-cooling molding. However, the mold used for casting is not limited to the semi-cylindrical copper mold listed above, and other commonly used alloy casting molds in the field are also applicable.

[0026] As a preferred solution, in step (5), water cooling is performed at a water flow rate of 2000-3000 L / h. The melt after high-temperature casting is water-cooled at a cooling rate of 2000-3000 L / h to increase the supercooling degree and nucleation rate; in addition, by controlling the above cooling rate, the excellent structure of the high-temperature melt can be retained to low temperature, improving the solid structure.

[0027] As a preferred solution, in step (5), cooling water is passed through the semi-cylindrical copper mold for water-cooling forming. After water-cooling forming, a semi-cylindrical ingot is obtained. According to the heat calculation formula Q=cm△t, the heat released when the melt of different casting temperatures is cooled to room temperature (25°C) can be calculated. In the formula, Q represents the heat absorbed or released by the substance, c is the specific heat capacity of the substance, the specific heat capacity of SnSb is 234.5J / K·℃, the specific heat capacity of water is 4.2×103J / K·℃, m represents the mass of the substance / cooling water flow rate, and △t is the temperature difference. When the water flow rate is 2000-3000L / h, it can effectively increase the cooling rate of the ingot and increase the supercooling degree and nucleation rate of the alloy.

[0028] As a preferred solution, the method for preparing the SnSb alloy preformed solder of the present invention, after the water-cooling forming in step (5), further comprises:

[0029] (6) Extrusion: Two semi-cylindrical ingots are spliced ​​into a cylinder, which is placed in an extrusion die cavity and extruded to obtain an extruded rod;

[0030] (7) Rolling: rolling the extruded rod into a strip of required thickness;

[0031] (8) Punching: Punching the material strip into SnSb alloy preformed solder materials of required size.

[0032] The present invention also provides a SnSb alloy preformed soft solder, which is prepared by any of the above-mentioned methods for preparing the SnSb alloy preformed soft solder.

[0033] Furthermore, the size of the intermetallic compound of the SnSb alloy preformed solder is ≤60 μm.

[0034] The size of the intermetallic compound of the SnSb alloy preformed solder of the present invention is lower than that of the general SnSb alloy, thereby improving the forming processing performance.

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] (1) The intermetallic compounds of the SnSb alloy preformed solder are small in size and evenly distributed.

[0037] (2) The processing and forming performance of the SnSb preformed solder is much higher than that of ordinary SnSb alloy, thereby improving the reliability of the SnSb alloy preformed solder used as solder.

[0038] (3) The equipment used in the preparation is all common industrial production equipment, with small equipment investment, which is conducive to the industrial production of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a method for preparing a SnSb alloy preformed solder;

[0040] Figure 2 The metallographic microstructures of the SnSb alloy preformed solders prepared in Example 1 (left) and Example 2 (right);

[0041] Figure 3 The metallographic microstructures of the SnSb alloy preformed solders prepared in Example 4 (left) and Example 5 (right);

[0042] Figure 4 The metallographic microstructures of the SnSb alloy preformed solders prepared in Comparative Example 1 (left) and Comparative Example 2 (right);

[0043] Figure 5 The metallographic microstructures of the SnSb alloy preformed solders prepared in Comparative Example 3 (left) and Comparative Example 6 (right);

[0044] Figure 6 The metallographic microstructures of the SnSb alloy preformed solders prepared in Comparative Example 7 (left) and Comparative Example 8 (right);

[0045] Figure 7 Metallographic microstructures of SnSb alloy preformed solders prepared in Comparative Example 9 (left) and Comparative Example 10 (right). DETAILED DESCRIPTION

[0046] The present invention provides a method for preparing SnSb alloy preformed solder. Figure 1 , including the following steps:

[0047] (1) Ingredients: High-purity Sn bars and high-purity Sb blocks are mixed into alloy raw materials in appropriate proportions;

[0048] (2) Alloy smelting: The alloy raw materials are loaded into a graphite crucible, placed in a resistance furnace for smelting and heat preservation, the smelting temperature is 800-950° C., and the heat preservation time is 20-40 min; after the melt is heat-insulated, stirred, and slag-stripped, step (3) is performed;

[0049] (3) Ultrasonic treatment: The ultrasonic process parameters are set to a power of 1-3 kW and a frequency of 20-23 kHz. The ultrasonic probe is inserted from the top into the melt by 1-5 cm and the ultrasonic treatment is performed for 1-5 min.

[0050] (4) High temperature casting: After the ultrasonic application is completed, the semi-cylindrical copper mold is used for casting immediately, and the casting temperature is 800-950°C;

[0051] (5) Water-cooling forming: Cooling water is passed through the semi-cylindrical copper mold at a water flow rate of 2000-3000 L / h, and a semi-cylindrical ingot is obtained after cooling and forming;

[0052] (6) Extrusion: Two semicircular ingots are spliced ​​into a cylinder, which is placed in an extrusion die cavity and extruded to obtain an extruded rod;

[0053] (7) Rolling: rolling the extruded rod into a strip of required thickness;

[0054] (8) Punching: Punching the material strip into SnSb alloy preformed solder materials of required size.

[0055] The present invention also provides a SnSb alloy preformed solder prepared by the preparation method, wherein the size of the intermetallic compound is ≤60 μm.

[0056] In order to better illustrate the problem to be solved by the technical solution of the present invention, the technical solution adopted and the beneficial effects achieved, it is now further described in conjunction with specific implementation methods. It is worth noting that the technical solution of the present invention includes but is not limited to the following implementation methods.

[0057] If no specific technology or conditions are specified in the examples of the present invention, the technology or conditions described in the literature in the field or the product instructions shall be followed. If the manufacturer of the materials or instruments used is not specified, they are all conventional products that can be obtained through commercial purchase or other channels.

[0058] Example 1

[0059] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0060] The preparation method of the SnSb alloy preformed solder of this embodiment can be found in Figure 1 , including the following steps:

[0061] (1) Ingredients: Weigh 4500 g of metallic tin and 500 g of metallic antimony (alloy raw material 1), and 4400 g of metallic tin and 600 g of metallic antimony (alloy raw material 2) respectively to prepare SnSb alloy raw materials of two alloy components, and perform the following steps on alloy raw material 1 and alloy raw material 2 respectively.

[0062] (2) Alloy smelting: The alloy raw materials are loaded into a graphite crucible and placed in a resistance furnace for smelting at a smelting temperature of 950° C. for 0.5 h. After the melt is kept warm, stirred, and slag is removed, step (3) is performed.

[0063] (3) Ultrasonic treatment: The ultrasonic process parameters were set to a power of 1 kW and a frequency of 20 kHz. The ultrasonic probe was inserted 2-3 cm into the melt from the top and ultrasonic treatment was performed for 1 min.

[0064] (4) High-temperature casting: After the ultrasonic wave is applied, casting is immediately carried out using a semi-cylindrical copper mold with a diameter of 10 cm and a height of 20 cm. The casting temperature is 950°C.

[0065] (5) Water-cooled forming: Cooling water is passed through the semi-cylindrical copper mold at a water flow rate of 3000 L / h. After cooling and forming, a semi-cylindrical ingot is obtained.

[0066] (6) Extrusion: Two semicircular ingots are spliced ​​into a cylinder, which is placed in a 450-ton extrusion die cavity for extrusion to obtain an extruded rod with a width of 70 mm and a thickness of 5 mm.

[0067] (7) Rolling: Roll the extruded rod into a strip of required thickness.

[0068] (8) Punching: Punching the material strip into SnSb alloy preformed solder materials of required size.

[0069] In this embodiment, the SnSb alloy preformed solder material finally made from alloy raw material 1 is recorded as SnSb10; the SnSb alloy preformed solder material finally made from alloy raw material 2 is recorded as SnSb12.

[0070] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0071] Example 2

[0072] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0073] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Example 1, except that: in this embodiment, the "power 1KW" in Example 1 is replaced by "power 3KW", and the rest of the processes are the same as those in Example 1.

[0074] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0075] Example 3

[0076] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0077] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Example 1, the difference is that: in this embodiment, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 900°C", and the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 900°C", and the rest of the processes are the same as those in Example 1.

[0078] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0079] Example 4

[0080] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0081] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Example 1, the difference is that: in this embodiment, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 850°C", and the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 850°C", and the rest of the processes are the same as those in Example 1.

[0082] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0083] Example 5

[0084] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0085] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Example 1, the difference is that: in this embodiment, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 800°C", and the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 800°C", and the rest of the processes are the same as those in Example 1.

[0086] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0087] Example 6

[0088] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0089] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Embodiment 1, except that: in this embodiment, the "frequency 20KHz" in Embodiment 1 is replaced by "frequency 23KHz", and the rest of the processes are the same as those in Embodiment 1.

[0090] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0091] Example 7

[0092] This embodiment provides a SnSb alloy preformed solder and a preparation method thereof.

[0093] The preparation method of the SnSb alloy preformed soft solder in this embodiment is basically the same as that in Example 1, except that: in this embodiment, the "ultrasonic treatment for 1 min" in Example 1 is replaced by "ultrasonic treatment for 5 min", and the rest of the processes are the same as those in Example 1.

[0094] Please refer to Table 1 for the control parameters and results during the preparation process of this embodiment.

[0095] Comparative Example 1

[0096] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0097] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, the difference is that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 750°C", and the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 750°C", and the rest of the processes are the same as those in Example 1.

[0098] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0099] Comparative Example 2

[0100] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0101] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, the difference is that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 1000°C", and the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 1000°C", and the rest of the processes are the same as those in Example 1.

[0102] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0103] Comparative Example 3

[0104] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0105] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, the difference is that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 800°C", the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 800°C", and the "power 1KW" in Example 1 is replaced by "power 0.8KW", and the remaining processes are the same as those in Example 1.

[0106] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0107] Comparative Example 4

[0108] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0109] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, the difference is that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by "melting temperature of 800°C", the "casting temperature of 950°C" in Example 1 is replaced by "casting temperature of 800°C", and the "frequency of 20KHz" in Example 1 is replaced by "frequency of 18KHz", and the rest of the processes are the same as those in Example 1.

[0110] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0111] Comparative Example 5

[0112] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0113] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, the difference is that: in this comparative example, the "ultrasonic treatment for 1 min" in Example 1 is replaced by "ultrasonic treatment for 0.5 min", and the rest of the processes are the same as those in Example 1.

[0114] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0115] Comparative Example 6

[0116] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0117] The preparation method of the SnSb alloy preformed solder of this comparative example is a common preparation method, comprising the following steps:

[0118] (1) Ingredients: Weigh 4500 g of metallic tin and 500 g of metallic antimony (alloy raw material 1), and 4400 g of metallic tin and 600 g of metallic antimony (alloy raw material 2) respectively to prepare SnSb alloy raw materials of two alloy components, and perform the following steps on alloy raw material 1 and alloy raw material 2 respectively.

[0119] (2) Alloy smelting: The alloy raw materials are loaded into a graphite crucible and placed in a resistance furnace for smelting at a smelting temperature of 400°C for 0.5 h.

[0120] (3) Casting: After the insulation is completed, casting is immediately carried out using a graphite mold at a casting temperature of 400°C to obtain an ingot.

[0121] (4) Extrusion: The ingot is placed in a 450-ton extrusion die cavity and extruded at a temperature of 120°C to obtain an extruded rod with a width of 70 mm and a thickness of 5 mm.

[0122] (5) Air cooling: Maximum air volume is 5800m 3 / h industrial fan cools the temperature of the extruded rod to room temperature after extrusion.

[0123] (6) Rolling: The extruded rod obtained in step (5) is rolled into a strip of required thickness.

[0124] (7) Punching: Punching the material strip in step (6) into SnSb alloy preformed solder materials of required size.

[0125] In this comparative example, the SnSb alloy preformed solder material finally made from alloy raw material 1 is also recorded as SnSb10; the SnSb alloy preformed solder material finally made from alloy raw material 2 is also recorded as SnSb12.

[0126] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0127] Comparative Example 7

[0128] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0129] The preparation method of the SnSb alloy preformed solder in this comparative example is basically the same as that in Example 1, except that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by a melting temperature of "400°C", and the "casting temperature of 950°C" in Example 1 is replaced by a "casting temperature of 400°C". The rest of the processes are the same as those in Example 1.

[0130] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0131] Comparative Example 8

[0132] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0133] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, except that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by the melting temperature of "400°C", the "casting temperature of 950°C" in Example 1 is replaced by the "casting temperature of 400°C", and the "(5) water-cooling forming: passing cooling water through the semi-cylindrical copper mold with a water flow rate of 3000L / h to obtain a semi-cylindrical ingot after cooling and forming" in Example 1 is replaced by "(5) air-cooling forming: using a maximum air volume of 5800m 3 / h industrial fan is used to reduce the temperature of the semi-cylindrical copper mold after casting to room temperature, and a semi-cylindrical ingot is obtained after air cooling. The rest of the process is the same as in Example 1.

[0134] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0135] Comparative Example 9

[0136] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0137] The preparation method of the SnSb alloy preformed soft solder in this comparative example is basically the same as that in Example 1, except that: in this comparative example, the "melting temperature of 950°C" in Example 1 is replaced by the melting temperature of "400°C", the "casting temperature of 950°C" in Example 1 is replaced by the "casting temperature of 400°C", the "ultrasonic treatment for 1 min" in Example 1 is replaced by the "ultrasonic treatment for 60 min", and the "(5) water-cooling forming: passing cooling water through the semi-cylindrical copper mold with a water flow rate of 3000 L / h to obtain a semi-cylindrical ingot after cooling and forming" in Example 1 is replaced by "(5) air-cooling forming: using a maximum air volume of 5800 m 3 The industrial fan with a speed of 1 / h lowers the temperature of the semi-cylindrical copper mold to room temperature after casting, and a semi-cylindrical ingot is obtained after air cooling.

[0138] The rest of the processes are the same as those in Example 1.

[0139] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0140] Comparative Example 10

[0141] This comparative example provides a SnSb alloy preformed solder and a preparation method thereof.

[0142] The preparation method of the SnSb alloy preformed solder of this embodiment can be found in Figure 1 , including the following steps:

[0143] (1) Ingredients: 4750 g of metallic tin and 250 g of metallic antimony were weighed separately to prepare an alloy raw material (alloy raw material 3).

[0144] (2) Alloy smelting: The alloy raw materials are loaded into a graphite crucible and placed in a resistance furnace for smelting at a smelting temperature of 400° C. for 0.5 h. After the melt is kept warm, stirred, and slag is removed, step (3) is performed.

[0145] (3) Casting: Use a semi-cylindrical copper mold with a diameter of 10 cm and a height of 20 cm for immediate casting at a casting temperature of 400°C.

[0146] (4) Air-cooled molding: Maximum air volume is 5800m 3 The industrial fan with a speed of / h lowers the temperature of the semi-cylindrical copper mold to room temperature after casting, and a semi-cylindrical ingot is obtained after air cooling.

[0147] (5) Extrusion: Two semicircular ingots are spliced ​​into a cylinder, which is placed in a 450-ton extrusion die cavity for extrusion to obtain an extruded rod with a width of 70 mm and a thickness of 5 mm.

[0148] (6) Rolling: Roll the extruded rod into a strip of required thickness.

[0149] (7) Punching: Punch the material strip into SnSb alloy preformed solder materials of required size.

[0150] In this comparative example, the SnSb alloy preformed solder material finally made from alloy raw material 3 is denoted as SnSb5.

[0151] Please refer to Table 1 for the control parameters and results during the preparation of this comparative example.

[0152] Table 1 Control parameters and results of Examples 1-7 and Comparative Examples 1-6

[0153]

[0154] Note: SnSb10 is a SnSb alloy preformed soft solder made from alloy raw material 1 of each pair of embodiments or comparative examples; SnSb12 is a SnSb alloy preformed soft solder made from alloy raw material 2 of each pair of embodiments or comparative examples; SnSb5 is a SnSb alloy preformed soft solder made from alloy raw material 3 of comparative example 10.

[0155] The preparation method of the SnSb alloy preformed soft solder of Examples 1-7 of the present invention prepares the SnSb alloy preformed soft solder by introducing ultrasonic treatment and combining high-temperature casting and water-cooling molding methods, which can effectively refine the intermetallic compounds of the SnSb alloy preformed soft solder, so that the prepared SnSb alloy preformed soft solder has small intermetallic compounds (size ≤ 60μm) and uniform distribution.

[0156] See also Figure 2 , Figure 2 The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Example 1 of the present invention (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Example 2 (right) are shown respectively. Figure 2 It can be seen that the intermetallic compounds of the SnSb alloy preformed solders prepared in Example 1 and Example 2 of the present invention are fine and evenly distributed in the matrix, and the size is less than 20 μm.

[0157] See also Figure 3 , Figure 3 The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Example 4 of the present invention (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Example 5 (right) are shown respectively. Figure 3It can be seen that the intermetallic compound size of the SnSb alloy preformed soft solder (SnSb10) prepared in Example 4 is mostly between 38-45μm; after the casting temperature is reduced to 800°C in Example 5, the melt structure transformation is incomplete due to the low casting temperature. The intermetallic compound size of the SnSb alloy preformed soft solder (SnSb10) prepared in Example 5 is mostly between 39-55μm, and a very small number of them are larger than 60μm, but the overall intermetallic compound size is ≤60μm, which still meets the requirements of the present invention.

[0158] In the preparation method of the SnSb alloy preformed soft solder of Comparative Example 1, the casting temperature is too low, and the size of the intermetallic compounds of the obtained SnSb alloy preformed soft solder is relatively large; in the preparation method of the SnSb alloy preformed soft solder of Comparative Example 2, the melting temperature and the casting temperature are too high. Although the size of the intermetallic compounds of the SnSb alloy preformed soft solder prepared in Comparative Example 2 is small, less than 60μm, the excessively high melting temperature and casting temperature make the alloy easily oxidized, and cause undesirable phenomena such as overburning, shrinkage cavities and looseness.

[0159] See also Figure 4 , Figure 4 The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 1 (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 2 (right). Figure 4 It can be seen that the low casting temperature leads to the large size of the intermetallic compounds in the metallographic microstructure of Comparative Example 1, and some of the sizes are between 80-100 μm. Although the size of the intermetallic compounds in Comparative Example 2 is small, less than 60 μm, the excessively high melting temperature and casting temperature will make the alloy easy to oxidize, overburn, shrinkage and looseness.

[0160] In the preparation methods of the SnSb alloy preformed soft solders of Comparative Examples 3, 4 and 5, the ultrasonic power is too low, the ultrasonic frequency is too low, and the ultrasonic treatment time is too short, respectively. The sizes of the intermetallic compounds of the SnSb alloy preformed soft solders prepared in Comparative Examples 3, 4 and 5 are relatively high.

[0161] The preparation method of the SnSb alloy preformed solder of Comparative Example 6 adopts the common casting method of SnSb alloy for preparation, and the intermetallic compounds of the prepared SnSb alloy preformed solder are particularly coarse.

[0162] See also Figure 5 , Figure 5The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 3 (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 6 (right). Figure 5 It can be seen that if the ultrasonic treatment power is low, the cavitation effect and acoustic streaming effect are weak, resulting in coarse intermetallic compounds of the SnSb alloy preformed soft solder (SnSb10) prepared in Comparative Example 3, most of which are between 70-90μm in size; the intermetallic compounds of the SnSb alloy preformed soft solder (SnSb10) prepared in Comparative Example 6 by ordinary casting method are coarse, and the maximum size reaches 150μm.

[0163] In the preparation method of the SnSb alloy preformed soft solder of Comparative Example 7, ultrasonic treatment, 400°C low-temperature casting, and water-cooling molding are adopted for preparation, and the intermetallic compounds of the obtained SnSb alloy preformed soft solder are relatively large in size; in the preparation method of the SnSb alloy preformed soft solder of Comparative Example 8, ultrasonic treatment, 400°C low-temperature casting, and air-cooling molding are adopted for preparation, and the intermetallic compounds of the obtained SnSb alloy preformed soft solder are particularly coarse.

[0164] See also Figure 6 , Figure 6 The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 7 (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 8 (right) are shown respectively. Figure 6 It can be seen that the comparative example 7 did not use high temperature casting, and the casting temperature was too low, resulting in the intermetallic compound size in the metallographic microstructure diagram of the SnSb alloy preformed solder (SnSb10) obtained in the comparative example 7 being too large, with a maximum size of 85.31 μm; the comparative example 8 did not use high temperature casting and did not use water cooling molding, resulting in the intermetallic compound in the metallographic microstructure diagram of the SnSb alloy preformed solder (SnSb10) obtained in the comparative example 8 being particularly coarse, with a maximum size of 143.5 μm. Compared with the embodiments 1-7 of the present invention, the comparative examples 7 and 8 cannot well refine the intermetallic compound by ultrasonic treatment alone or by casting in a combination of ultrasonic and water cooling.

[0165] The preparation method of the SnSb alloy preformed solder of Comparative Example 9 adopts the method of extending the ultrasonic time (60 minutes), low-temperature casting at 400°C, and air-cooling molding to prepare the SnSb alloy preformed solder. The size of the intermetallic compound of the prepared SnSb alloy preformed solder is relatively large. The preparation method of the SnSb alloy preformed solder of Comparative Example 10 uses the alloy raw material 3 as the raw material to prepare the SnSb alloy preformed solder. The prepared SnSb alloy preformed solder has no precipitation of intermetallic compounds.

[0166] See also Figure 7 , Figure 7 The metallographic microstructures of the SnSb alloy preformed solder (SnSb10) prepared in Comparative Example 9 (left) and the metallographic microstructures of the SnSb alloy preformed solder (SnSb5) prepared in Comparative Example 10 (right) are shown respectively. Figure 7 It can be seen that comparative example 9 is prepared by long-term ultrasonic treatment, 400°C low-temperature casting and air-cooling molding, and the maximum size of the intermetallic compounds of the obtained SnSb alloy preformed soft solder is 86.53μm; the SnSb alloy preformed soft solder (SnSb5) of comparative example 10 is a SnSb alloy with an antimony weight content of 5%, and no intermetallic compounds are precipitated during the casting process.

[0167] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A method for preparing a SnSb alloy preformed solder, characterized in that: The following steps are involved: (1) Batching: preparing metallic tin and metallic antimony into alloy raw materials; (2) Alloy smelting: melting the alloy raw materials into a melt and keeping it warm; the smelting temperature is 800-950°C; (3) Ultrasonic treatment: ultrasonic treatment of the melt; wherein the ultrasonic power is not less than 1 kW, the ultrasonic frequency is not less than 20 kHz, and the ultrasonic treatment time is not less than 1 min; (4) High temperature casting: Casting the ultrasonically treated melt at a casting temperature of 800-950°C; (5) Water cooling forming; The SnSb alloy preformed solder is obtained.

2. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (3), the ultrasonic power is 1-3KW, the ultrasonic frequency is 20-23KHz, and the ultrasonic treatment time is 1-5min.

3. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (3), the ultrasonic treatment is carried out from the top, and the ultrasonic probe is inserted into the melt from the top by 1-5 cm.

4. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (5), water cooling is performed at a water flow rate of 2000-3000 L / h.

5. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (1), the weight content of metal antimony in the alloy raw material is 10-12%.

6. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (2), a resistance furnace is used for smelting, and the holding time is 20-40 minutes; after the melt is held, stirred, and deslagging, step (3) i.e. ultrasonic treatment is performed.

7. The method for preparing the SnSb alloy preformed solder according to claim 1, characterized in that: In step (4), a semi-cylindrical copper mold is used for casting; in step (5), cooling water is passed through the semi-cylindrical copper mold for water-cooling molding, and after water-cooling molding, a semi-cylindrical ingot is obtained.

8. The method for preparing the SnSb alloy preformed solder according to claim 7, characterized in that: After step (5) of water-cooling forming, the method further comprises: (6) Extrusion: Two semi-cylindrical ingots are spliced ​​into a cylinder, which is placed in an extrusion die cavity and extruded to obtain an extruded rod; (7) Rolling: rolling the extruded rod into a strip of required thickness; (8) Punching: Punching the material strip into SnSb alloy preformed soft solder of required size.

9. A SnSb alloy preformed solder, characterized in that: The SnSb alloy preformed solder is prepared by the preparation method of any one of claims 1-8.

10. The SnSb alloy preform solder according to claim 9, characterized in that: The size of its intermetallic compounds is ≤60μm.

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