Silver-copper-titanium active soldering paste with high recovery coefficient, and preparation method and application thereof

Abstract

The application relates to a silver-copper-titanium active soldering paste with a high recovery coefficient and a preparation method and application thereof, and belongs to the technical field of heterogeneous material connection and semiconductor packaging. The silver-copper-titanium active soldering paste is composed of the following mass percentage materials: solder powder 70-90%, and flux 10-30%; the solder powder is a mixed powder composed of a silver-copper-based powder, a titanium-containing powder and other metal powders; the flux is composed of the following mass percentage materials: solvent 40-70%, rosin 20-40%, active agent 5-20%, thixotropic agent 1-15%, interface modifier 1-10% and corrosion inhibitor 1-10%; the thixotropic agent is composed of a short-range agent and a long-range agent at a mass ratio of 1:1-4. The obtained soldering paste has a recovery coefficient close to 1, excellent printing suitability, anti-flowing property and storage stability, and has a wide application prospect in the fields of semiconductor packaging, power electronic devices and aerospace.

Description

Technical Field

[0001] This invention relates to a high recovery coefficient silver-copper-titanium active solder paste, its preparation method and application, belonging to the fields of heterogeneous material bonding technology and semiconductor packaging technology. Background Technology

[0002] In high-end equipment manufacturing fields such as power electronics and aerospace, achieving reliable bonding between ceramics and metals is of paramount importance. However, due to significant differences in the physical and chemical properties of ceramics and metals, conventional brazing filler metals are insufficient to effectively wet ceramic surfaces, thus requiring active metal brazing technology. Currently, Ag-Cu-Ti alloys are the most widely used active brazing filler metals, achieving high-strength metallurgical bonding through the chemical reaction between titanium and ceramics. However, these filler metals are currently mainly processed into foil strips, which have several limitations: firstly, poor shape adaptability, making them unsuitable for complex structures or micro-sized workpieces, and hindering assembly and positioning; secondly, low compositional adjustability and high manufacturing costs.

[0003] Solder paste, as an ideal alternative, can achieve high-precision and automated application through printing, dot coating, and other processes, significantly improving production efficiency and process adaptability. However, existing silver-copper-titanium active solder pastes still have significant shortcomings in rheological properties, especially poor thixotropy, with a coefficient of recovery far below 1. This leads to various process defects in practical applications: First, poor printing quality, with delayed viscosity recovery during high-speed printing, easily causing pattern distortion, bridging, or edge defects; second, insufficient anti-sagging performance, causing the paste to flow after application to vertical or curved substrates, resulting in uneven solder distribution and even short-circuit risks; finally, component segregation and phase separation are prone to occur during storage and transportation, affecting the component uniformity of the solder and the performance stability of the final joint. Therefore, developing a silver-copper-titanium active solder paste with both a high coefficient of recovery and excellent comprehensive performance is key to solving the above problems. Summary of the Invention

[0004] To address the issue of poor thixotropic properties in existing silver-copper-titanium active solder pastes, this invention proposes a silver-copper-titanium active solder paste with a high coefficient of recovery, its preparation method, and its applications. By synergistically adjusting the composition, proportions, and preparation process of the solder paste, this invention yields a silver-copper-titanium active solder paste with excellent thixotropic properties and a coefficient of recovery approaching 1. This significantly improves its capabilities in printing, anti-sagging, and storage stability, thereby effectively ensuring the process adaptability and joint reliability of ceramic-metal bonding processes, providing an innovative bonding material solution for high-end equipment manufacturing.

[0005] A high recovery coefficient silver-copper-titanium active solder paste, wherein the solder paste is composed of the following materials by mass percentage: 70%-90% solder powder and 10%-30% flux; wherein the solder powder is a mixed powder composed of silver-copper based powder, titanium-containing powder and other metal powders; wherein the flux is composed of the following materials by mass percentage: 40%-70% solvent, 20%-40% rosin, 5%-20% activator, 1%-15% thixotropic agent, 1%-10% interface modifier, and 1%-10% corrosion inhibitor, wherein the thixotropic agent is composed of short-range agent and long-range agent in a mass ratio of 1:1-4.

[0006] Preferably, the solder powder has a mass percentage of 80%-90%, and the flux has a mass percentage of 10%-20%.

[0007] More preferably, the solder powder has a mass percentage of 85%-90%, and the flux has a mass percentage of 10%-15%.

[0008] Furthermore, in the above technical solution, the silver-copper based powder is a mixed powder of silver powder and copper powder or a silver-copper alloy powder.

[0009] Furthermore, in the above technical solution, the titanium-containing powder is titanium powder or titanium hydride powder.

[0010] Furthermore, in the above technical solution, the other metal powder is selected from one or more of gold, lithium, aluminum, tin, indium, zinc, nickel, chromium, gallium, zirconium, palladium, lanthanum or cerium.

[0011] Furthermore, in the above technical solution, the mass percentage of silver in the brazing filler powder is 0.1%-90%; preferably 15%-90%; more preferably 40%-90%.

[0012] Furthermore, in the above technical solution, the mass percentage of copper in the brazing filler powder is 0.1%-90%; preferably 10%-90%; more preferably 20%-50%.

[0013] Furthermore, in the above technical solution, the mass percentage of titanium in the brazing filler powder is 0.1%-70%; preferably 0.1%-30%; more preferably 0.1%-15%.

[0014] Furthermore, in the above technical solution, the mass percentage of other metals in the brazing filler powder is 0.1%-30%; preferably 0.1%-15%; more preferably 0.1%-10%.

[0015] Furthermore, in the above technical solution, the average particle size of the silver-copper-based powder, titanium-containing powder, and other metal powder in the solder powder is independently selected from 0.1-300 μm; preferably 0.1-100 μm; more preferably 0.1-30 μm.

[0016] Furthermore, in the above technical solution, the short-range agent is hydrogenated castor oil.

[0017] Furthermore, in the above technical solution, the long-range agent is one of polyamide, polyamide wax, ethyl cellulose, or polyurea.

[0018] Furthermore, in the above technical solution, the solvent is one or more of terpineol, diethylene glycol butyl ether acetate, dioctyl adipate, or dioctyl azelate.

[0019] Furthermore, in the above technical solution, the activator is one or more of potassium fluoroborate, potassium fluoride, cesium fluoride, or lithium fluoride.

[0020] Furthermore, in the above technical solution, the interface modifier is one or more of aminopropyltriethoxysilane, propyltrimethoxysilane, or dialkyl phosphate.

[0021] Furthermore, in the above technical solution, the corrosion inhibitor is one or more of benzotriazole, monoethanolamine, triethanolamine, or 2-methylimidazole.

[0022] Another object of the present invention is to provide a method for preparing the above-mentioned silver-copper-titanium active solder paste, comprising the following steps: (1) Weigh silver-copper-based powder, titanium-containing powder and other metal powders according to the proportion, and ball mill them at a speed of 20-500 r / min for 1-20 h. After ball milling, dry them at 60-200 ℃ for 10-200 min to obtain brazing filler metal powder. (2) Add the solvent and rosin to the ultrasonic disperser, heat to 60-75 ℃ and disperse for 30-120 min until the rosin is completely dissolved and a uniform and transparent liquid is formed; (3) Add the activator to the liquid described in step (2) and ultrasonically disperse it at 60-75 °C for 10-60 min until the activator is completely dispersed and mixed evenly to obtain a mixed solution; (4) Add the thixotropic agent to the mixed solution described in step (3), heat to 80-90 ℃ and then ultrasonically disperse for 20-90 min. The thixotropic agent is evenly dispersed to form a uniform transparent colloid. (5) Stop heating, add the interface modifier to the colloid in step (4) and ultrasonically disperse for 1-4 h until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel. (6) Add the corrosion inhibitor to the gel described in step (5) and ultrasonically disperse it at room temperature for 5-40 min until it is uniformly dispersed to obtain a viscous paste-like flux. (7) Mix the flux obtained in step (6) with the solder powder obtained in step (1) and stir it in a vacuum mixer for 10-60 min at room temperature to obtain a bright, bubble-free solder paste.

[0023] Furthermore, in the above technical solution, in step (1), the ball milling time is preferably 10-20 h; more preferably 15-20 h.

[0024] Furthermore, in the above technical solution, in step (1), the ball milling speed is preferably 150-500 r / min; more preferably 200-300 r / min.

[0025] Furthermore, in the above technical solution, in step (1), the drying time is preferably 100-200 min; more preferably 150-200 min.

[0026] Furthermore, in the above technical solution, in step (1), the drying temperature is preferably 80-200 ℃; more preferably 120-200 ℃.

[0027] Furthermore, in the above technical solution, in step (2), the ultrasonic dispersion time is preferably 60-120 min; more preferably 90-120 min.

[0028] Furthermore, in the above technical solution, in step (3), the ultrasonic dispersion time is preferably 30-60 min; more preferably 30-40 min.

[0029] Furthermore, in the above technical solution, in step (4), the ultrasonic dispersion time is preferably 40-80 min; more preferably 40-60 min.

[0030] Furthermore, in the above technical solution, in step (5), the ultrasonic dispersion time is preferably 2-4 h; more preferably 2-3 h.

[0031] Furthermore, in the above technical solution, in step (6), the ultrasonic dispersion time is preferably 10-40 min; more preferably 20-40 min.

[0032] Furthermore, in the above technical solution, in step (7), the vacuum stirring time is preferably 30-60 min; more preferably 30-40 min.

[0033] Another objective of this invention is to provide the application of the aforementioned high recovery coefficient silver-copper-titanium active solder paste in heterogeneous material bonding technology and semiconductor packaging.

[0034] The beneficial effects of this invention: This invention relates to a high-recovery-coefficient silver-copper-titanium active solder paste and its preparation method, belonging to the fields of heterogeneous material joining technology and semiconductor packaging. This invention employs a "short-range-long-range" synergistic thixotropic system, enabling the rapid reconstruction of the three-dimensional network structure of the solder paste after shearing. Simultaneously, an interface modifier is introduced to effectively prevent the erosion of the thixotropic agent by titanium, significantly improving the thixotropic properties of the solder paste, making its recovery coefficient close to 1. This key improvement effectively solves the shortcomings of traditional silver-copper-titanium active solder pastes in terms of printability, anti-sagging ability, and storage stability. The solder paste obtained by this invention possesses excellent printability, enabling the printing of fine patterns with clear outlines and full lines, meeting the stringent requirements of high-density packaging for solder coating; it also exhibits excellent anti-sagging performance (vertical sagging height <0.5 mm), and can be stably coated on vertical walls and complex three-dimensional structure surfaces; furthermore, the solder paste has good storage stability, effectively inhibiting particle sedimentation and phase separation, ensuring uniform composition and consistent performance. This invention provides an innovative approach for high-precision, automated ceramic-metal bonding, and is particularly suitable for high-end equipment manufacturing fields such as aerospace thermal protection systems, high-power electronic device packaging, and high-temperature and high-pressure sensors. Attached Figure Description

[0035] Figure 1 This is a photograph of the silver-copper-titanium active solder paste prepared in Example 1. Detailed Implementation

[0036] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0037] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0038] The solder paste recovery coefficient described in the following examples was measured by a RheolabQC rotational rheometer manufactured by Anton Paar (Shanghai) Trading Co., Ltd.

[0039] Example 1 In the preparation of flux, terpineol is selected as the solvent, potassium fluoroborate as the activator, hydrogenated castor oil as the short-range agent, polyamide wax as the long-range agent, aminopropyltriethoxysilane as the interface modifier, and benzotriazole as the corrosion inhibitor.

[0040] Prepare silver-copper-titanium active solder paste according to the following steps: (1) Weigh out 54.8 g of silver powder with an average particle size of 150 μm, 21.2 g of copper powder with an average particle size of 30 μm and 4 g of titanium powder with an average particle size of 220 μm according to the mass percentage of 68.5: 26.5: 5. Mix them by ball milling at 300 r / min for 6 h. After ball milling, dry them at 100 ℃ for 60 min to obtain brazing filler metal powder. (2) Add 11 g of terpineol and 6 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.6 g of potassium fluoroborate to the above liquid and ultrasonically disperse at 65 °C for 30 min to obtain a mixed solution; (4) Add 0.4 g hydrogenated castor oil and 0.8 g polyamide wax to the above mixed solution, heat to 85 °C, and ultrasonically disperse for 60 min to form a uniform transparent colloid; (5) Stop heating, add 1.5 g of aminopropyltriethoxysilane to the above colloid, ultrasonically disperse for 2.5 h, and let it cool naturally to room temperature, gradually thicken, lose transparency, and form a uniform paste-like gel. (6) Add 0.2 g of benzotriazole to the above gel and continue to disperse it ultrasonically at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6), and stir under vacuum for 30 min in a vacuum mixer to obtain silver-copper-titanium solder paste, which has the following appearance. Figure 1 As shown.

[0041] The solder paste obtained in this embodiment showed a recovery coefficient R(60 s) of 0.92, vertical sagging of 0.27 mm, no significant settling after 168 h, a spreading rate of 78% on AlN ceramic, and full printed patterns. The shear strength of the AlN / Cu brazed joint made with it as a solder was 128 MPa.

[0042] Example 2 In the preparation of flux, diethylene glycol butyl ether acetate is selected as solvent, potassium fluoride as activator, hydrogenated castor oil as short-path agent, polyurea as long-path agent, propyltrimethoxysilane as interface modifier, and 2-methylimidazole as corrosion inhibitor.

[0043] Prepare silver-copper-titanium active solder paste according to the following steps: (1) Weigh out 55.25 g of silver powder with an average particle size of 300 μm, 25.075 g of copper powder with an average particle size of 30 μm and 4.675 g of titanium hydride powder with an average particle size of 150 μm according to the mass percentage of 65:29.5:5.5. Mix them by ball milling at 350 r / min for 8 h. After ball milling, dry them at 110 ℃ for 80 min to obtain brazing filler metal powder. (2) Add 9 g of diethylene glycol butyl ether acetate and 3.75 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.2 g of potassium fluoride to the above liquid and ultrasonically disperse at 60 °C for 30 min to obtain a mixed solution; (4) Add 0.3 g hydrogenated castor oil and 0.45 g polyurea to the above mixed solution, heat to 88 °C, and ultrasonically disperse for 70 min to form a uniform transparent colloid; (5) Stop heating, add 1 g of propyltrimethoxysilane to the above colloid, ultrasonically disperse for 2.5 h, until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel; (6) Add 0.3 g of 2-methylimidazole to the above gel and continue to disperse it by ultrasonication at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 10 min to obtain silver-copper-titanium solder paste.

[0044] Tests showed that the solder paste obtained in this embodiment had a recovery coefficient R(60 s) = 0.95, vertical sag = 0.09 mm, no significant sedimentation after standing for 168 h, a spreading rate of 80% on Si3N4 ceramic, and full printed patterns. The shear strength of the Si3N4 / 4J36 brazed joint made by using it as a solder was 131 MPa.

[0045] Example 3 In the preparation of the flux, dioctyl adipate is selected as the solvent, lithium fluoride as the activator, hydrogenated castor oil as the short-path agent, ethyl cellulose as the long-path agent, dialkyl phosphate as the interface modifier, and triethanolamine as the corrosion inhibitor.

[0046] Prepare silver-copper-tin-titanium active solder paste according to the following steps: (1) Weigh out 70.2 g of silver-copper alloy powder with an average particle size of 10 μm, 3.12 g of titanium powder with an average particle size of 20 μm and 4.68 g of tin powder with an average particle size of 15 μm according to the mass percentage of 90:4:6. Mix them by ball milling at 400 r / min for 10 h. After ball milling, dry them at 90 ℃ for 90 min to obtain brazing filler metal powder. (2) Add 14.3 g of dioctyl adipate and 5.06 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.54 g of lithium fluoride to the above liquid and ultrasonically disperse it at 60 °C for 30 min to obtain a mixed solution; (4) Add 0.27 g hydrogenated castor oil and 0.5 g ethyl cellulose to the above mixed solution, heat to 83 °C, disperse for 50 min to form a uniform transparent colloid; (5) Stop heating, add 1.2 g of dialkyl phosphate to the above colloid, ultrasonically disperse for 2.5 h, until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel; (6) Add 0.33 g of triethanolamine to the above gel and continue to ultrasonically disperse at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 20 min to obtain silver-copper-tin-titanium solder paste.

[0047] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.89, vertical sagging of 0.37 mm, no significant settling after 168 h, a spreading rate of 76% on ZrO2 ceramic, and full printed patterns. The shear strength of the ZrO2 / TZM brazed joint made using this solder was 115 MPa.

[0048] Example 4 In the preparation of the flux, terpineol is selected as the solvent, potassium fluoroborate and cesium fluoride as activators, hydrogenated castor oil as a short-range agent, polyamide wax as a long-range agent, aminopropyltriethoxysilane as an interface modifier, and benzotriazole as a corrosion inhibitor.

[0049] Prepare silver-copper-nickel-cerium-titanium active solder paste according to the following steps: (1) Weigh out 79.2 g of silver-copper alloy powder with an average particle size of 200 μm, 5.28 g of titanium hydride powder with an average particle size of 100 μm, 1.76 g of nickel powder with an average particle size of 5 μm and 1.76 g of cerium powder with an average particle size of 15 μm according to the mass percentage of 90:6:2:2. Mix them by ball milling at 280 r / min for 12 h. After ball milling, dry them at 115 ℃ for 100 min to obtain brazing filler metal powder. (2) Add 6 g of terpineol and 4.2 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 0.6 g potassium fluoroborate and 0.6 g cesium fluoride to the above liquid and disperse it by ultrasonication at 70 °C for 30 min to obtain a mixed solution; (4) Add 0.2 g hydrogenated castor oil and 0.22 g polyamide wax to the above mixed solution, heat to 86 °C, disperse for 80 min to form a uniform transparent colloid; (5) Stop heating, add 0.7 g aminopropyltriethoxysilane, ultrasonically disperse for 2.5 h, and let it cool naturally to room temperature. It will gradually thicken, lose transparency, and form a uniform paste-like gel. (6) Add 0.18 g of benzotriazole to the above gel and continue to ultrasonically disperse at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 25 min to obtain silver-copper-nickel-cerium-titanium solder paste.

[0050] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.9, vertical sag of 0.44 mm, no significant settling after 168 h, a spreading rate of 77% on Al2O3 ceramic, and full printed patterns. The Al2O3 / Invar alloy brazed joint prepared using this solder exhibited a shear strength of 145 MPa.

[0051] Example 5 In the preparation of flux, terpineol is selected as solvent, potassium fluoride as activator, hydrogenated castor oil as short-path agent, polyamide as long-path agent, propyltrimethoxysilane as interface modifier, and monoethanolamine as corrosion inhibitor.

[0052] Prepare silver-copper-titanium active solder paste according to the following steps: (1) Weigh out 56.8 g of silver powder with an average particle size of 50 μm, 19.2 g of copper powder with an average particle size of 230 μm and 4 g of titanium powder with an average particle size of 25 μm according to the mass percentage of 71:24:5. Mix them by ball milling at 250 r / min for 5 h. After ball milling, dry them at 95 ℃ for 70 min to obtain brazing filler metal powder. (2) Add 9 g of terpineol and 8 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1 g of potassium fluoride to the above liquid and ultrasonically disperse it at 70 °C for 30 min to obtain a mixed solution; (4) Add 0.3 g of hydrogenated castor oil and 0.5 g of polyamide to the above mixed solution, heat to 82 °C, disperse for 40 min, and form a uniform transparent colloid; (5) Stop heating, add 0.5 g of propyltrimethoxysilane to the above colloid, and ultrasonically disperse for 2.5 h until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel. (6) Add 0.2 g of monoethanolamine to the above gel and continue to disperse it ultrasonically at room temperature for 20 min to obtain flux; (7) Mix the brazing powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 30 min to obtain silver-copper-titanium solder paste.

[0053] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.88, vertical sag of 0.12 mm, no significant settling after 168 h, a spreading rate of 75% on SiC ceramic, and full printed patterns. The shear strength of the SiC / TC4 brazed joint made using this solder was 120 MPa.

[0054] Example 6 In the preparation of flux, dioctyl adipate is selected as solvent, lithium fluoride as activator, hydrogenated castor oil as short-path agent, polyamide wax as long-path agent, dialkyl phosphate as interface modifier, and 2-methylimidazole as corrosion inhibitor.

[0055] Prepare silver-copper-titanium active solder paste according to the following steps: (1) Weigh out 66.5 g of silver-copper alloy powder with an average particle size of 250 μm, 1.75 g of titanium powder with an average particle size of 30 μm and 1.75 g of zinc powder with an average particle size of 10 μm according to the mass percentage of 95:2.5:2.5. Mix them by ball milling at 450 r / min for 20 h. After ball milling, dry them at 80 ℃ for 120 min to obtain brazing filler metal powder. (2) Add 21 g of dioctyl adipate and 6 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.5 g of lithium fluoride to the above liquid and ultrasonically disperse it at 75 °C for 30 min to obtain a mixed solution; (4) Add 0.4 g hydrogenated castor oil and 0.8 g polyamide wax to the above mixed solution, heat to 80 °C, disperse for 90 min to form a uniform transparent colloid; (5) Stop heating, add 2.5 g of dialkyl phosphate to the above colloid, ultrasonically disperse for 2.5 h, until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel; (6) Add 0.3 g of 2-methylimidazole to the above gel and continue to disperse it by ultrasonication at room temperature for 20 min to obtain flux; (7) Mix the brazing powder obtained in step (1) with the flux obtained in step (6) and vacuum stir in a vacuum mixer for 60 min to obtain silver-copper-titanium solder paste.

[0056] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.93, vertical sagging of 0.17 mm, no significant settling after 168 h, a spreading rate of 79% on diamond ceramics, and full printed patterns. The shear strength of the diamond / Kovar alloy brazed joint made using this solder was 125 MPa.

[0057] Example 7 In the flux preparation process, terpineol is selected as the solvent, potassium fluoride as the activator, hydrogenated castor oil as the short-range agent, ethyl cellulose as the long-range agent, aminopropyltriethoxysilane as the interface modifier, and benzotriazole as the corrosion inhibitor.

[0058] Prepare silver-copper-nickel-titanium active solder paste according to the following steps: (1) Weigh out 58.93 g of silver powder with an average particle size of 80 μm, 19.92 g of copper powder with an average particle size of 300 μm, 3.735 g of titanium hydride powder with an average particle size of 20 μm and 0.415 g of nickel powder with an average particle size of 50 μm according to the mass percentage of 71:24:4.5:0.5. Mix them by ball milling at 320 r / min for 7 h. After ball milling, dry them at 105 ℃ for 80 min to obtain brazing filler metal powder. (2) Add 10.2 g of terpineol and 4.76 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.02 g of potassium fluoride to the above liquid and ultrasonically disperse it at 65 °C for 30 min to obtain a mixed solution; (4) Add 0.34 g hydrogenated castor oil and 0.34 g ethyl cellulose to the above liquid, heat to 84 °C, disperse for 60 min to form a uniform transparent colloid; (5) Stop heating, add 1 g of aminopropyltriethoxysilane to the above colloid, ultrasonically disperse for 2.5 h, until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel; (6) Add 0.34 g of benzotriazole to the above gel and continue to ultrasonically disperse at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 15 min to obtain silver-copper-nickel-titanium solder paste.

[0059] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.91, vertical sag of 0.48 mm, no significant settling after 168 h, and a spreading rate of 80% on ZrB2 ceramic, resulting in a full printed pattern. The shear strength of the ZrB2 / TZM brazed joint made using this solder was 138 MPa.

[0060] Example 8 In the flux preparation process, terpineol is selected as the solvent, potassium fluoroborate as the activator, hydrogenated castor oil as the short-range agent, polyamide as the long-range agent, propyltrimethoxysilane as the interface modifier, and triethanolamine as the corrosion inhibitor.

[0061] Prepare silver-copper-titanium active solder paste according to the following steps: (1) Weigh out 53.6 g of silver powder with an average particle size of 40 μm, 22.4 g of copper powder with an average particle size of 10 μm and 4 g of titanium powder with an average particle size of 300 μm according to the mass percentage of 67:28:5. Mix them by ball milling at 270 r / min for 4.5 h. After ball milling, dry them at 100 ℃ for 60 min to obtain brazing filler metal powder. (2) Add 14 g of terpineol and 5 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 0.6 g of potassium fluoroborate to the above liquid and disperse it by ultrasonication at 75 °C for 30 min to obtain a mixed solution; (4) Add 0.13 g of hydrogenated castor oil and 0.17 g of polyamide to the above mixed solution, heat to 85 °C, disperse for 30 min, and form a uniform transparent colloid; (5) Stop heating, add 1.6 g of propyltrimethoxysilane to the above colloid, ultrasonically disperse for 2.5 h, and let it cool naturally to room temperature, gradually thicken, lose transparency, and form a uniform paste-like gel. (6) Add 0.1 g of triethanolamine to the above gel and continue to ultrasonically disperse at room temperature for 20 min to obtain flux; (7) Mix the brazing powder obtained in step (1) with the flux obtained in step (6) and vacuum stir in a vacuum mixer for 50 min to obtain silver-copper-titanium solder paste.

[0062] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.87, vertical sagging of 0.35 mm, no significant settling after 168 h, a spreading rate of 74% on Al2O3 ceramic, and full printed patterns. The Al2O3 / C-276 brazed joint made using this solder exhibited a shear strength of 118 MPa.

[0063] Example 9 In the flux preparation process, diethylene glycol butyl ether acetate is selected as the solvent, potassium fluoride as the activator, hydrogenated castor oil as the short-path agent, polyamide wax as the long-path agent, dialkyl phosphate as the interface modifier, and benzotriazole as the corrosion inhibitor.

[0064] Prepare silver-copper-indium-titanium active solder paste according to the following steps: (1) Weigh out 72.93 g of silver-copper alloy powder with an average particle size of 20 μm, 3.9 g of titanium hydride powder with an average particle size of 150 μm and 1.17 g of indium powder with an average particle size of 200 μm according to the mass percentage of 93.5: 5: 1.5. Mix them by ball milling at 330 r / min for 9 h. After ball milling, dry them at 115 ℃ for 90 min to obtain brazing filler metal powder. (2) Add 11 g of diethylene glycol butyl ether acetate and 6.6 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 2.2 g of potassium fluoride to the above liquid and ultrasonically disperse at 65 °C for 30 min to obtain a mixed solution; (4) Add 0.5 g of hydrogenated castor oil and 1.26 g of polyamide wax to the above mixed solution, heat to 90 °C, disperse for 90 min, and form a uniform transparent colloid; (5) Stop heating, add 0.6 g of dialkyl phosphate to the above colloid, ultrasonically disperse for 2.5 h, and let it cool naturally to room temperature, gradually thicken, lose transparency, and form a uniform paste gel; (6) Add 0.44 g of benzotriazole to the above gel and continue to disperse it ultrasonically at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 40 min to obtain silver copper indium titanium solder paste.

[0065] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.96, vertical sag of 0.07 mm, no significant settling after 168 h, a spreading rate of 77% on Si3N4 ceramic, and a full printed pattern. The shear strength of the Si3N4 / 4J29 brazed joint made using this solder was 110 MPa.

[0066] Example 10 In the flux preparation process, terpineol is selected as the solvent, cesium fluoride as the activator, hydrogenated castor oil as the short-range agent, polyurea as the long-range agent, aminopropyltriethoxysilane as the interface modifier, and 2-methylimidazole as the corrosion inhibitor.

[0067] Prepare silver-copper-tin-gallium-zirconium-titanium active solder paste according to the following steps: (1) Weigh out 49.8 g of silver powder with an average particle size of 15 μm, 16.6 g of copper powder with an average particle size of 230 μm, 3.32 g of titanium hydride powder with an average particle size of 100 μm, 8.3 g of tin powder with an average particle size of 70 μm, 2.49 g of gallium powder with an average particle size of 5 μm and 2.49 g of zirconium powder with an average particle size of 120 μm according to the mass percentage of 60:20:4:10:3:3. Mix them by ball milling at 380 r / min for 15 h. After ball milling, dry them at 120 ℃ for 110 min to obtain solder powder. (2) Add 10.2 g of terpineol and 4.76 g of rosin to an ultrasonic disperser, heat to 70 °C, disperse for 60 min to form a uniform and transparent liquid; (3) Add 1.19 g of cesium fluoride to the above liquid and ultrasonically disperse it at 70 °C for 30 min to obtain a mixed solution; (4) Add 0.25 g of hydrogenated castor oil and 0.345 g of polyurea to the above mixed solution, heat to 88 °C, disperse for 70 min, and form a uniform transparent colloid; (5) Stop heating, add 0.4 g aminopropyltriethoxysilane and 0.5 g dialkyl phosphate to the above colloid, ultrasonically disperse for 2.5 h, until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste gel; (6) Add 0.255 g of 2-methylimidazole to the above gel and continue to disperse it by ultrasonication at room temperature for 20 min to obtain flux; (7) Mix the solder powder obtained in step (1) with the flux obtained in step (6) and stir in a vacuum mixer for 35 min to obtain silver-copper-tin-gallium-zirconium-titanium solder paste.

[0068] Testing revealed that the solder paste obtained in this embodiment had a coefficient of restitution R(60 s) of 0.89, vertical sag of 0.19 mm, no significant settling after 168 h, a spreading rate of 81% on SiC ceramic, and full printed patterns. The shear strength of the SiC / TC4 brazed joint made using this solder was 122 MPa.

[0069] Comparative Example 1 In the preparation of the flux, terpineol was selected as the solvent, potassium fluoroborate as the activator, hydrogenated castor oil as the thixotropic agent, aminopropyltriethoxysilane as the interface modifier, and benzotriazole as the corrosion inhibitor.

[0070] The difference between this comparative example and Example 1 is that only hydrogenated castor oil was selected as the thixotropic agent, no long-range agent was added, the amount of hydrogenated castor oil added was 1.2 g, and all other operations were the same as in Example 1.

[0071] Tests showed that the solder paste obtained in this comparative example had a recovery coefficient R(60 s) of 0.74, vertical sagging of 2.4 mm, significant settling after standing for 48 hours, a spreading rate of 56% on AlN ceramics, and collapsed printed patterns.

[0072] Comparative Example 2 In the preparation of the flux, terpineol is selected as the solvent, potassium fluoroborate as the activator, polyamide wax as the thixotropic agent, aminopropyltriethoxysilane as the interface modifier, and benzotriazole as the corrosion inhibitor.

[0073] The difference between this comparative example and Example 1 is that only polyamide wax was selected as the thixotropic agent, no short-range agent was added, the amount of polyamide wax added was 1.2 g, and the rest of the operations were the same as in Example 1.

[0074] Tests showed that the solder paste obtained in this comparative example had a recovery coefficient R(60 s) of 0.7, vertical sagging of 1.6 mm, significant settling after standing for 52 h, a spreading rate of 56% on AlN ceramics, and collapse of the printed pattern.

[0075] Comparative Example 3 In the preparation of flux, terpineol is selected as the solvent, potassium fluoroborate as the activator, hydrogenated castor oil as the short-path agent, polyamide wax as the long-path agent, and benzotriazole as the corrosion inhibitor.

[0076] The difference between this comparative example and Example 1 is that no interface modifier was added, while all other operations are the same as in Example 1.

[0077] Tests showed that the solder paste obtained in this comparative example had a recovery coefficient R(60 s) of 0.8, vertical sagging of 1.4 mm, significant settling after standing for 60 hours, a spreading rate of 64% on AlN ceramics, and collapsed printed patterns.

Claims

1. A high recovery coefficient silver-copper-titanium active solder paste, characterized in that: The solder paste is composed of the following materials by weight percentage: 70%-90% solder powder and 10%-30% flux; the solder powder is a mixed powder composed of silver-copper based powder, titanium-containing powder and other metal powders; the flux is composed of the following materials by weight percentage: 40%-70% solvent, 20%-40% rosin, 5%-20% activator, 1%-15% thixotropic agent, 1%-10% interface modifier, and 1%-10% corrosion inhibitor, wherein the thixotropic agent is composed of short-range agent and long-range agent in a mass ratio of 1:1-4; The short-range agent is hydrogenated castor oil; the long-range agent is one of polyamide, polyamide wax, ethyl cellulose, or polyurea. The activator is one or more of potassium fluoroborate, potassium fluoride, cesium fluoride, or lithium fluoride; The interface modifier is one or more of aminopropyltriethoxysilane, propyltrimethoxysilane, or dialkyl phosphate; The corrosion inhibitor is one or more of benzotriazole, monoethanolamine, triethanolamine or 2-methylimidazole; The preparation method of the silver-copper-titanium active solder paste includes the following steps: (1) Weigh silver-copper-based powder, titanium-containing powder and other metal powders according to the proportion, and ball mill them at a speed of 20-500 r / min for 1-20 h. After ball milling, dry them at 60-200 ℃ for 10-200 min to obtain brazing filler metal powder. (2) Add the solvent and rosin to the ultrasonic disperser, heat to 60-75 ℃ and then ultrasonically disperse for 30-120 min until the rosin is completely dissolved and a uniform and transparent liquid is formed. (3) Add the activator to the liquid described in step (2) and ultrasonically disperse it at 60-75 °C for 10-60 min until the activator is completely dispersed and mixed evenly to obtain a mixed solution; (4) Add the thixotropic agent to the mixed solution described in step (3), heat to 80-90 ℃ and then ultrasonically disperse for 20-90 min. The thixotropic agent is evenly dispersed to form a uniform transparent colloid. (5) Stop heating, add the interface modifier to the colloid in step (4) and ultrasonically disperse for 1-4 h until it cools naturally to room temperature, gradually thickens, loses transparency, and forms a uniform paste-like gel. (6) Add the corrosion inhibitor to the gel described in step (5) and ultrasonically disperse it at room temperature for 5-40 min until it is uniformly dispersed to obtain a viscous paste-like flux. (7) Mix the flux obtained in step (6) with the solder powder obtained in step (1) and stir it in a vacuum mixer for 10-60 min at room temperature to obtain a bright, bubble-free solder paste.

2. The silver-copper-titanium active solder paste according to claim 1, characterized in that: The silver-copper-based powder is a mixture of silver powder and copper powder or a silver-copper alloy powder; the titanium-containing powder is titanium powder or titanium hydride powder; the other metal powder is selected from one or more of gold, lithium, aluminum, tin, indium, zinc, nickel, chromium, gallium, zirconium, palladium, lanthanum or cerium.

3. The silver-copper-titanium active solder paste according to claim 1, characterized in that: The solder powder contains 0.1%-90% silver, 0.1%-90% copper, 0.1%-70% titanium, and 0.1%-30% other metals by mass.

4. The silver-copper-titanium active solder paste according to claim 1, characterized in that: The average particle size of the silver-copper-based powder, titanium-containing powder, and other metal powders in the brazing filler metal powder is independently selected from 0.1-300 μm.

5. The silver-copper-titanium active solder paste according to claim 1, characterized in that: The solvent is one or more of terpineol, diethylene glycol butyl ether acetate, dioctyl adipate, or dioctyl azelate.

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