Preparation method of Y / Ge composite modified AuSn-based amorphous brazing filler metal

Abstract

The invention discloses a preparation method of Y / Ge composite modified AuSn-based amorphous brazing filler metal, and relates to the field of amorphous brazing materials. The invention discloses an Au-Sn-Ge alloy which is composed of the following components in percentage by mass: 70-80 wt% of Au, 16.5-22 wt% of Sn, 3-5 wt% of rare earth element Y and 0.5-3 wt% of Ge. The rare earth elements Y and Ge are added to modify the amorphous brazing filler metal, so that the amorphous forming ability of the amorphous brazing filler metal is remarkably enhanced, the critical cooling rate of the alloy is reduced, the crystallization initial temperature of an AuSnYGe amorphous brazing filler metal strip is greatly increased, the amorphous phase retention rate after annealing is about 98.5%, the brazing wettability is remarkably optimized, the wetting angle of the Kovar alloy is reduced to 12 degrees from 25 degrees, and the brazing performance is improved. The fluidity of the brazing filler metal is obviously improved.

Description

Technical Field

[0001] The patent of this invention belongs to the field of amorphous brazing materials, specifically a Y / Ge composite modified AuSn-based amorphous brazing material. Background Art

[0002] AuSn eutectic alloy (Au-20wt.% Sn) amorphous foil has become the preferred lead-free solder for high-end scenarios such as high-frequency chip packaging and high-power laser welding due to its high thermal conductivity, low vapor pressure and excellent creep resistance. However, its core component design has inherent defects: uncontrollable brittle phase, high oxygen sensitivity and limited single alloy system. Under traditional processes, the Au-Sn system will inevitably form brittle intermetallic compounds of Au5Sn (ζ phase) and AuSn (δ phase) during solidification, resulting in low elongation of the foil and high fracture rate during cold rolling. At the same time, a high residual oxygen content can easily induce interfacial oxidation (SnO2 layer thickness > 50nm), significantly deteriorating wettability. In addition, the pure binary system lacks element modulation ability and has a high melt viscosity, making it difficult to fully fill narrow gaps, which seriously restricts its application in high-density packaging.

[0003] Existing preparation processes further amplify compositional defects: the laminated cold rolling method causes composition segregation due to oxidation of the Sn layer; the electroplating deposition method reduces the interface bonding strength due to contamination by Fe and Cu impurities; and although the single-roller strip spinning method can achieve amorphization, the proportion of amorphous phase is insufficient and the thermal stability is poor. The essence of these problems stems from the inability of the traditional AuSn composition system to regulate the atomic-scale structure, which cannot suppress the precipitation and oxidation tendency of the brittle phase, and it is difficult to optimize the melt fluidity and interfacial reaction activity. Patent CN108340097B "Composite Amorphous Solder Strip Preparation Method" discloses a method for preparing a composite amorphous solder strip, which is prepared by configuring equipment, melting and constant-pressure spraying of solder, and collecting and compounding amorphous solder foil strips. However, the composite amorphous solder strip prepared by this method has the problems of being brittle at room temperature, poor processability, and difficult to mass produce.

[0004] Therefore, the development of multi-component composite modification technology has become a key path to break through the bottleneck - by introducing rare earth elements such as Y and metalloid Ge, reconstructing the short-range ordered structure of the alloy, synergistically inhibiting the growth of brittle phases, reducing oxygen content, and improving the amorphous formation ability, thereby meeting the urgent needs of electronic packaging for high reliability, ultra-thinness and multi-specification solders. Summary of the Invention

[0005] In order to solve the technical problems of high brittleness, poor processability and difficulty in mass production of amorphous solders manufactured by the prior art, the present invention proposes a method for preparing an AuSn-based amorphous solder containing a Y / Ge composite modification. The AuSn-based amorphous solder containing a Y / Ge composite modification prepared by this method has the advantages of uniform composition, dense structure, excellent welding performance, etc., and can also achieve control of strip thickness.

[0006] The specific technical solutions of the present invention are:

[0007] A Y / Ge composite modified AuSn-based amorphous solder comprises the following components in percentage by mass: Au: 69.5-77 wt%, Sn: 19.5-22.5 wt%, rare earth element Y: 3-5 wt%, and Ge: 0.5-3 wt%.

[0008] A method for preparing a Y / Ge composite-modified AuSn amorphous solder comprises the following steps: S1. Au and Sn are weighed according to the mass ratio and placed in a vacuum induction melting furnace. Rare earth elements Y and Ge are added to obtain an AuSnYGe alloy ingot. S2. The AuSnYGe alloy ingot is placed in a quartz crucible, the quartz crucible is placed vertically in the induction coil, and fixed to the fixed frame of the strip throwing device; S3 closed the upper end opening of the quartz crucible, and inject a protective gas; start the induction heating device, adjust the induction heating frequency, heating the AuSnYGe alloy ingot to a molten state to obtain a uniform composition of the AuSnYGe alloy liquid; S4. Start the single-roller strip-spinning device, adjust the speed of the cooling copper roller, and adjust the pressure difference in the cavity so that the AuSnYGe alloy liquid is sprayed onto the surface of the cooling copper roller for rapid cooling to form AuSnYGe amorphous solder.

[0009] Preferably, the rare earth element Y is added in the form of a high-purity Y ingot with a purity of ≥99.9%; Ge is added in the form of a high-purity Ge ingot in the late stage of smelting, and the melt temperature is 1100±50°C when added.

[0010] Preferably, the purity of the Au ingot in step S1 is ≥99.9%; the purity of the Sn ingot is ≥99.9%.

[0011] Higher purity can ensure the stability of the subsequent alloy composition and eliminate the impact of impurities on the performance of subsequent products.

[0012] Preferably, the mass ratio of Au to Sn in step S1 is 4:1.

[0013] Controlling the mass ratio of Au and Sn can ensure the stability of the subsequent amorphous solder composition.

[0014] Preferably, the heating frequency in step S3 is 30-40 kHz.

[0015] The heating frequency is controlled to transform the alloy into a molten state.

[0016] Preferably, the protective gas in step S3 is argon.

[0017] Heat treatment under argon protection can effectively prevent oxidation of metal Sn.

[0018] Preferably, the copper roller in step S4 has a rotation speed of 10-40 m / s.

[0019] At this rotation speed, the fluidity of liquid Au and Sn can be effectively guaranteed to be consistent, overcoming the uneven deformation caused by the different yield stresses of solid Au and Sn.

[0020] Preferably, the nozzle in step S4 has a width of 1 mm and a length of 5-15 mm.

[0021] Preferably, the pressure difference in step S4 is 60-90 kPa.

[0022] Under this pressure difference, it is easy to control the ejection speed of the alloy liquid and facilitate the subsequent formation of amorphous solder.

[0023] Beneficial effects:

[0024] The present invention produces an amorphous brazing strip. The single-roll strip-spinning rapid solidification technology employed by the present invention allows the AuSnYGe alloy liquid to cool rapidly on the roller surface, resulting in uniform composition, compact structure, and excellent welding performance, while also enabling control over the strip thickness. Compared to existing laminated cold-rolling composite technologies, the single-roll strip-spinning process of the present invention ensures consistent fluidity between liquid Au and Sn, overcoming the uneven deformation caused by the different yield stresses of solid Au and Sn. The subsequent heat treatment process is carried out under a protective atmosphere, effectively preventing oxidation of Sn in the brazing material. Consequently, the present invention produces a uniformly composed, high-purity AuSnYGe amorphous brazing strip. Compared to existing technologies, the present invention offers the advantages of simple process operation, low cost, high efficiency, and controllable strip thickness.

[0025] Compared with the traditional AuSn amorphous ribbon, the AuSnYGe composite modified amorphous foil prepared by the present invention has achieved a significant breakthrough in comprehensive performance: through the synergistic effect of rare earth Y and Ge, its amorphous forming ability is significantly enhanced - Y induces local atomic stacking distortion and forms Y5Sn3 metastable phase, combined with the interference of Ge atomic covalent bond network on the Au-Sn short-range ordered structure, which reduces the critical cooling rate of the alloy and broadens the supercooled liquid phase region; in terms of mechanical properties, the solid solution strengthening of Y and the synergistic effect of the bonding network of Ge increase the Vickers hardness by about 18%, the yield strength by about 30%, and the fracture toughness by about 10%. The thermal stability and brazing performance of the AuSn amorphous foil are improved by approximately 50% and the fracture strain by 15%. In terms of thermal stability and brazing performance, the crystallization onset temperature is increased to 220°C (heating rate 20K / min), and the amorphous phase retention rate after annealing is ≥98.5%. The Y / Ge composite effect reduces the melt surface tension to 0.45N / m (wetting angle optimized to 12°). The Au-Ge low-melting-point eutectic phase introduced by Ge increases the solder fluidity by 40%, and the interfacial shear strength is increased by 30% compared to ordinary AuSn amorphous foil. The thin and uniform thickness of the strip, low oxygen content, and uniform composition of each section of the solder strip can improve the welding effect and have little impact on the subsequent brazing performance. This significantly broadens the process window and improves welding reliability.

[0026] In summary, the present invention directly produces AuSnYGe amorphous solder strips with excellent plasticity, high purity, and uniform composition from Au and Sn ingots. This not only overcomes the brittleness of AuSn alloys, which prevents them from being processed into strips, but also reduces production costs and simplifies the manufacturing process. The present invention is simple to operate, produces strips with controllable thickness, and has a short process cycle and low costs, making it promising for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Attachment Figure 1 It is a schematic diagram of the single-roller strip-spinning rapid solidification device of the present invention.

[0028] Attachment Figure 2 This is a photo of the AuSnYGe amorphous foil ribbon described in the present invention.

[0029] In the figure, 1-quartz crucible, 2-induction coil, 3-nozzle, 4-AuSnYGe amorphous solder strip, 5-water-cooled copper roller. DETAILED DESCRIPTION

[0030] In order to better illustrate the technical effects of the present invention, the following is an analysis in conjunction with specific embodiments and comparative examples.

[0031] Overall embodiment:

[0032] In an oxygen-free environment, Au ingots, Sn ingots and Y ingots are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, a high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1 mm. The upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40 kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with a chrome-plated surface. The system cools the copper roller system with a water flow rate of 20L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30m / s, the argon pressure difference inside and outside the quartz crucible is adjusted so that the AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip; the rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous ribbon prepared by this method has a thickness of 70 μm and a width of 10 mm; the nozzle width is 1 mm and the length is 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder ribbon obtained by strip spinning is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing ribbon with good plasticity.

[0033] Example 1

[0034] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 3g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 1g of high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with chrome plating on the surface. The copper roller system is cooled by a water cooling system. The temperature is lowered with a water flow rate of 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 90 kPa. The AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip. The rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous strip prepared by this method has a thickness of 70 μm and a width of 10 mm; the nozzle has a width of 1 mm and a length of 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder strip obtained by strip spinning is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0035] Example 2

[0036] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 3g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 2g of high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with a chrome-plated surface. The copper roller system is cooled by a water cooling system. The temperature is lowered with a water flow rate of 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 90 kPa. The AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip. The rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous strip prepared by this method has a thickness of 70 μm and a width of 10 mm; the nozzle has a width of 1 mm and a length of 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder strip obtained by strip spinning is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0037] Example 3

[0038] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 3g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 3g of high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with chrome plating on the surface. The copper roller system is cooled by a water cooling system. The temperature is lowered with a water flow rate of 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 70 kPa. The AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip. The rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous strip prepared by this method has a thickness of 50 μm and a width of 10 mm; the nozzle has a width of 1 mm and a length of 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder strip obtained by strip spinning is annealed at 250° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0039] Example 4

[0040] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 4g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 3g of high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with chrome plating on the surface. The copper roller system is cooled by a water cooling system. The temperature is lowered with a water flow rate of 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 70 kPa. The AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip. The rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous strip prepared by this method has a thickness of 50 μm and a width of 10 mm; the nozzle has a width of 1 mm and a length of 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder strip obtained by strip spinning is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0041] Example 5

[0042] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 5g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 3g of high-purity Ge ingot is added and the melting is continued to form an AuSnYGe alloy ingot. The smelted AuSnYGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnYGe alloy ingot is heated until it is completely melted to obtain an AuSnYGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with chrome plating on the surface. The copper roller system is cooled by a water cooling system. The temperature is lowered with a water flow rate of 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure adjustment. After adjusting the roller speed to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 70 kPa. The AuSnYGe alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSnYGe alloy liquid is rapidly cooled on the roller surface to obtain AuSnYGe amorphous strip. The rapidly cooled amorphous strip is peeled off with a ceramic scraper and wound to a winder. The AuSnYGe amorphous strip prepared by this method has a thickness of 50 μm and a width of 10 mm; the nozzle has a width of 1 mm and a length of 10 mm; the purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%; the AuSnYGe amorphous solder strip obtained by strip spinning is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0043] Example 6

[0044] In an oxygen-free environment, 80g of Au ingot, 20g of Sn ingot and 3g of Y ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing, thereby forming an AuSnY alloy ingot. The smelted AuSnY alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end, the quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device, the distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnY alloy ingot is heated until it is completely melted to obtain an AuSnY alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with a chrome-plated surface. The copper roller system is cooled by a water cooling system with a water flow rate of 20L / m in, the copper roller system is placed in a vacuum chamber to facilitate subsequent pressure differential adjustment. After the roller speed is adjusted to 30 m / s, the argon pressure differential between the inside and outside of the quartz crucible is adjusted to 70 kPa, so that the AuSnY alloy liquid is sprayed onto the copper roller through a nozzle and moves along the roller surface. The AuSnY alloy liquid is rapidly cooled on the roller surface to obtain an AuSnY amorphous strip. The quenched amorphous strip is peeled off with a ceramic scraper and wound onto a winder. The AuSnY amorphous strip prepared according to the present method has a thickness of 50 μm and a width of 10 mm. The nozzle width is 1 mm and the length is 10 mm. The purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%. The AuSnY amorphous solder strip obtained by stripping is annealed at 250° C. for 30 minutes in a protective atmosphere composed of argon gas to obtain a brazing strip with good plasticity.

[0045] Example 7

[0046] In an oxygen-free environment, 80g of Au ingot and 20g of Sn ingot are placed in a vacuum induction furnace for melting, and electromagnetic stirring is performed during the melting process to ensure uniform mixing. When the melt temperature reaches 1100°C, 1g of high-purity Ge ingot is added and the melting is continued to form an AuSnGe alloy ingot. The smelted AuSnGe alloy ingot is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end. The quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device. The distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve. The air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSnGe alloy ingot is heated until it is completely melted to obtain an AuSnGe alloy liquid with uniform composition. The single-roller belt-spinning device is turned on, and the copper roller is made of high-thermal-conductivity oxygen-free copper with chrome plating on the surface. A water cooling system is used to cool the copper roller system. The method comprises the following steps: a first step is to heat the copper roller system, and the second step is to heat the copper roller system to a temperature of 30 m / s, and the water flow rate is 20 L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure differential adjustment. After the roller speed is adjusted to 30 m / s, the argon pressure differential between the inside and outside of the quartz crucible is adjusted to 70 kPa, so that the AuSnGe alloy liquid is sprayed onto the copper roller through a nozzle and moves along the roller surface. The AuSnGe alloy liquid is rapidly cooled on the roller surface to obtain an AuSnGe amorphous strip. The quenched amorphous strip is peeled off with a ceramic scraper and wound onto a winder. The AuSnGe amorphous strip prepared according to the method has a thickness of 50 μm and a width of 10 mm. The nozzle width is 1 mm and the length is 10 mm. The purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%. The AuSnGe amorphous solder strip obtained by stripping is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon gas to obtain a brazing strip with good plasticity.

[0047] Comparative Example 1

[0048] In an oxygen-free environment, 80g of Au ingot and 20g of Sn ingot are placed in a vacuum induction furnace for melting. Electromagnetic stirring is performed during the melting process to ensure uniform mixing, and finally an AuSn alloy ingot is formed; the AuSn alloy ingot obtained by melting is placed in a quartz crucible with an opening at the upper end and a nozzle at the lower end, the quartz crucible is vertically placed in an induction coil and fixed on a fixed frame of a belt-spinning device, the distance between the nozzle and the cooling copper roller is controlled to be 1mm, and the upper opening of the quartz crucible is sealed with a sealing device with an air inlet valve; the air inlet valve is opened to fill the quartz crucible with argon gas, and then the induction heating furnace is turned on, the induction heating frequency is adjusted to 40kHz, and the AuSn alloy ingot is heated until it is completely melted to obtain an AuSn alloy liquid with uniform composition; the single-roller belt-spinning device is turned on, the copper roller is made of high-thermal-conductivity oxygen-free copper with a chrome-plated surface, and a water cooling system is used to cool the copper roller system, and the water flow rate is 20L / min. The copper roller system is placed in a vacuum chamber to facilitate subsequent pressure differential adjustment. After the roller speed is adjusted to 30 m / s, the argon pressure difference inside and outside the quartz crucible is adjusted to 90 kPa, so that the AuSn alloy liquid is sprayed onto the copper roller through the nozzle and moves with the roller surface. The AuSn alloy liquid is rapidly cooled on the roller surface to obtain an AuSn amorphous strip. The quenched amorphous strip is peeled off with a ceramic scraper and wound onto a winder. The AuSn amorphous strip prepared according to this method has a thickness of 70 μm and a width of 10 mm. The nozzle width is 1 mm and the length is 10 mm. The purity of the Au ingot is ≥99.999%; the purity of the Sn ingot is ≥99.99%; and the purity of the Y ingot is ≥99.9%. The AuSn amorphous solder strip obtained by stripping is annealed at 200° C. for 30 minutes in a protective atmosphere composed of argon to obtain a brazing strip with good plasticity.

[0049] Performance tests were performed on Examples 1-7 and Comparative Example 1. The specific test methods are as follows:

[0050] Oxygen content test:

[0051] Determination of oxygen content in amorphous solder using pulsed heating inert gas fusion-infrared method:

[0052] Take 100mg of amorphous solder, ultrasonically clean it with ethanol to remove surface contaminants, dry it, and wrap it in tin foil. Using the standard oxygen content sample calibration curve, place the amorphous solder sample in a graphite crucible and heat it to 3000℃ under helium protection. After the sample melts, it releases CO in the form of CO, which is catalytically oxidized to CO2 and quantified using an infrared detector. The oxygen content of the sample is calculated after deducting the background value of the empty crucible.

[0053] Melting point test:

[0054] Determination of the melting point of amorphous solder using differential scanning calorimetry:

[0055] Take 10 mg of amorphous solder sample, clean it with ethanol ultrasonically, use nitrogen as the protective atmosphere, heat it at a rate of 20°C / min until the amorphous solder is completely melted, and record the melting point of the amorphous solder.

[0056] Wettability test:

[0057] Determination of the wetting properties of solder using the sessile drop method: The substrate was polished and cut into regular small pieces of 3×3×1 mm. Nitrogen was used as the protective atmosphere and the temperature was raised to the brazing temperature at a rate of 20°C / min. The droplet morphology was recorded by a high-speed camera, and finally the wetting angle was measured using image processing software.

[0058] The test results are shown in the following table: Brazing base material Brazing process Oxygen content (ppm) Melting point (℃) Wetting angle (°) Example 1 <![CDATA[Al2O3]]> 280℃ / 3min 20 267 20 Example 2 <![CDATA[Al2O3]]> 275℃ / 2min 25 260 16 Example 3 <![CDATA[Al2O3]]> 270℃ / 2min 30 255 15 Example 4 <![CDATA[Al2O3]]> 265℃ / 1min 18 252 13 Example 5 <![CDATA[Al2O3]]> 260℃ / 1min 12 250 12 Example 6 <![CDATA[Al2O3]]> 290℃ / 4min 15 272 27 Example 7 <![CDATA[Al2O3]]> 285℃ / 3min 50 271 22 Comparative Example 1 <![CDATA[Al2O3]]> 300℃ / 5min 35 278 30

[0059] Subsequent tests found that the crystallization starting temperature of the AuSnYGe amorphous solder strip was greatly improved, the amorphous phase retention rate after annealing was about 98.5%, the brazing wettability was significantly optimized, the wetting angle for Kovar alloy was reduced from 25° to 12°, and the fluidity of the solder was significantly improved.

[0060] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A Y / Ge composite modified AuSn-based amorphous solder, characterized in that: The invention comprises the following components in percentage by mass: Au: 69.5-77 wt%, Sn: 19.5-22.5 wt%, rare earth element Y: 3-5 wt%, Ge: 0.5-3 wt%.

2. A method for preparing a Y / Ge composite modified AuSn-based amorphous solder, characterized in that: The steps include: S1. The Au ingot and Sn ingot were weighed by mass and placed in a vacuum induction melting furnace, rare earth elements Y and Ge were added, and AuSnYGe alloy ingots were obtained by melting; S2. The AuSnYGe alloy ingot is placed in a quartz crucible, the quartz crucible is placed vertically in the induction coil, and fixed to the fixed frame of the strip throwing device; S3 closed the upper end opening of the quartz crucible, and inject a protective gas; start the induction heating device, adjust the induction heating frequency, heating the AuSnYGe alloy ingot to a molten state to obtain a uniform composition of the AuSnYGe alloy liquid; S4. Start the single-roller strip-spinning device, adjust the speed of the cooling copper roller, and adjust the pressure difference in the cavity so that the AuSnYGe alloy liquid is sprayed through the nozzle to the surface of the cooling copper roller for rapid cooling to form AuSnYGe amorphous solder.

3. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 2, characterized in that: In step S1, Y is added in the form of high-purity Y ingots with a purity of ≥99.9%; Ge is added in the form of high-purity Ge ingots in the late stage of smelting, and the melt temperature is 1100±50°C when added.

4. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 2, characterized in that: In step S1 , the purity of the Au ingot is ≥99.9%; the purity of the Sn ingot is ≥99.9%.

5. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 4, characterized in that: The mass ratio of Au to Sn in step S1 is 4:

1.

6. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 2, characterized in that: The heating frequency in step S3 is 30-40 kHz.

7. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 6, characterized in that: The protective gas in step S3 is argon.

8. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 2, characterized in that: The copper roller rotation speed in step S4 is 10-40 m / s.

9. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to claim 8, characterized in that: The nozzle described in step S4 has a width of 1 mm and a length of 5-15 mm.

10. The method for preparing a Y / Ge composite-modified AuSn-based amorphous solder according to any one of claims 2 to 9, characterized in that: The pressure difference in step S4 is 60-90 kPa.

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