A method for high-temperature heat treatment of silver-palladium alloy powder

Abstract

The application discloses a high-temperature heat treatment method of silver-palladium alloy powder, which comprises the following steps: weighing superfine silver-palladium powder and pouring it into deionized water for hydrothermal reaction, preparing a dispersant and a coating agent solution, adding the solution into a hydrothermal reaction kettle, heating and keeping the hydrothermal reaction kettle, and carrying out hydrothermal coating; then, the solution in the hydrothermal reaction kettle is centrifugally separated into solid and liquid phases, washed, dried, and crushed to obtain coated silver-palladium alloy powder; the silver-palladium alloy powder and salt are mixed according to a required proportion, and then placed in a muffle furnace and heated to a required temperature; after keeping the temperature, a high-temperature heat treatment silver-palladium alloy powder and salt mixture is obtained; finally, the mixture is washed, dried, and crushed to obtain the high-temperature heat treatment silver-palladium alloy powder. The application can prepare the silver-palladium alloy powder with a size of 1.5-2.5 microns and a tap density of 4.2-6.0 g / cm 3 .

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of noble metal powder material preparation, and relates to a high-temperature heat treatment method of silver-palladium alloy powder. BACKGROUND

[0002] Silver is the most conductive and heat-conductive among all metals, and is the cheapest among noble metals. Silver also has good processability. Palladium can overcome two defects of silver ion migration and poor resistance to solder immersion corrosion of silver as conductive material in the microelectronic industry. And greatly improves the reliability of microelectronic devices, thereby becoming a conductive functional filler of electronic paste that attracts much attention. Whether the parameters such as particle size, morphology, particle size distribution, tap density and surface state of silver-palladium alloy are superior or not will have an important influence on the performance.

[0003] At present, the preparation methods of silver-palladium alloy include physical methods and chemical methods. The chemical method is mainly adopted in large-scale production due to its lower production cost and easy control. However, the silver-palladium alloy powder prepared by the chemical method has a particle size of 300-2000nm, a tap density of about 3.0g / cm 3 , and defects in surface roughness, low tap density and alloying. SUMMARY

[0004] In order to solve the above problems, the application provides a high-temperature heat treatment method of silver-palladium alloy powder to obtain silver-palladium alloy powder with smooth surface, good alloying and high tap density in view of the defects of the existing silver-palladium alloy heat treatment technology.

[0005] The technical scheme adopted by the application to solve the technical problems is as follows: a high-temperature heat treatment method of silver-palladium alloy powder, comprising the following steps:

[0006] Step one, 50g of ultra-fine silver-palladium powder with a particle size distribution D50 of 300-2000nm and 200mL of deionized water are weighed and poured into a hydrothermal reaction kettle for stirring, then a dispersant of 10-100 times the mass of the ultra-fine silver-palladium powder is added, and after the silver-palladium powder is completely dispersed in the water, a coating agent of 3.3-20 times the mass of the ultra-fine silver-palladium powder is added for continuous stirring;

[0007] Step two, the hydrothermal reaction kettle is heated to 120-300℃ for 1-24h for hydrothermal coating, and the solution in the hydrothermal reaction kettle is centrifuged to separate the solid and liquid phases, washed, dried, and crushed to obtain the coated silver-palladium alloy powder during continuous stirring;

[0008] Step three, the coated silver-palladium alloy powder and the ultra-fine silver-palladium powder are mixed uniformly with 1-30 times the mass of salt;

[0009] Step four, the mixture of the obtained silver-palladium alloy powder and salt is heated to 300-900 DEG C in a muffle furnace for 0.5-4 h, and the obtained high-temperature heat-treated mixture is washed, dried, and crushed to obtain a silver-palladium alloy powder with a particle size distribution D50 of 1.5-2.5 μm and a tap density of 4.2-6.0 g / cm 3 .

[0010] The dispersing agent of the high-temperature heat treatment method of the silver-palladium alloy powder is polyvinylpyrrolidone, polyethylene glycol, or gum arabic.

[0011] The coating agent of the high-temperature heat treatment method of the silver-palladium alloy powder is glucose or tannic acid.

[0012] The salt of the high-temperature heat treatment method of the silver-palladium alloy powder is a water-soluble inorganic salt such as sodium chloride or anhydrous sodium sulfate, or an organic salt such as an aldehyde.

[0013] The present application has the following advantages and positive effects:

[0014] 1. The method of the present application controls the particle size of the silver-palladium alloy powder and improves the effect of preventing the silver-palladium alloy powder from agglomerating at high temperatures by controlling the coating agent and the amount, the hydrothermal temperature and time, and the type and proportion of the salt.

[0015] 2. The method of the present application reduces the activity of the silver-palladium powder, increases the alloying degree, and increases the tap density by changing the heat treatment temperature and time.

[0016] 3. The ultra-fine silver-palladium powder with a particle size distribution D50 of 300-2000 nm can be treated by the high-temperature heat treatment method of the present application to have a particle size of 1.5-2.5 μm and a tap density of 4.2-6.0 g / cm 3 . BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 1 of the present application;

[0018] Figure 2 The SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 2 of the present application;

[0019] Figure 3 The SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 3 of the present application;

[0020] Figure 4 The SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 4 of the present application. DETAILED DESCRIPTION

[0021] The application will be described in detail below by way of examples and drawings, which are further used to illustrate the application, but cannot be understood as limiting the scope of protection of the application. Example 1

[0022] The high-temperature heat treatment method of the silver-palladium alloy powder disclosed in this example comprises the following steps.

[0023] Step one, weigh 50g of 400nm ultra-fine silver-palladium powder into a hydrothermal reactor 200mL of deionized water and stir, add 10 times the mass of polyethylene glycol as a dispersant to the ultra-fine silver-palladium powder, and after the silver-palladium powder is completely dispersed in the water, add 3.3 times the mass of glucose as a coating agent to continue stirring.

[0024] Step two, heat the hydrothermal reactor to 120℃ and keep it at this temperature for 24h to perform hydrothermal coating, and continuously stir during the process. After the coating is completed, centrifuge the solution in the hydrothermal reactor to separate the solid and liquid phases, wash, dry, and crush to obtain the coated silver-palladium alloy powder.

[0025] Step three, mix the coated silver-palladium alloy powder and 1 times the mass of sodium chloride with the ultra-fine silver-palladium powder uniformly.

[0026] Step four, place the mixture of the silver-palladium alloy powder and sodium chloride obtained in step three in a muffle furnace and heat it to 300℃, keep it at this temperature for 4h to obtain a mixture of high-temperature heat treated silver-palladium alloy powder and sodium chloride, and finally wash, dry, and crush to obtain the high-temperature heat treated silver-palladium alloy powder. As shown in the SEM analysis, Figure 1 the particle size distribution D50 of the silver-palladium alloy powder is 2.5μm, and the tap density is 4.2g / cm 3 . Example 2

[0027] The high-temperature heat treatment method of the silver-palladium alloy powder disclosed in this example comprises the following steps.

[0028] Step one, weigh 50g of 400nm ultra-fine silver-palladium powder into a hydrothermal reactor 200mL of deionized water and stir, add 10 times the mass of polyethylene glycol as a dispersant to the ultra-fine silver-palladium powder, and after the silver-palladium powder is completely dispersed in the water, add 3.3 times the mass of glucose as a coating agent to continue stirring.

[0029] Step two, heat the hydrothermal reactor to 120℃ and keep it at this temperature for 24h to perform hydrothermal coating, and continuously stir during the process. After the coating is completed, centrifuge the solution in the hydrothermal reactor to separate the solid and liquid phases, wash, dry, and crush to obtain the coated silver-palladium alloy powder.

[0030] Step three, mix the coated silver-palladium alloy powder and 1 times the mass of sodium chloride with the ultra-fine silver-palladium powder uniformly.

[0031] Step four, the mixture of silver palladium alloy powder obtained in step three and anhydrous sodium sulfate is placed in a muffle furnace and heated to 500°C, and a high-temperature heat-treated mixture of silver palladium alloy powder and anhydrous sodium sulfate is obtained after 3h of heat preservation. Finally, the high-temperature heat-treated silver palladium alloy powder is obtained after washing, drying, and crushing. Through SEM analysis as shown in FIG. 1, the particle size distribution D50 of the silver palladium alloy powder is 2.0 μm, and the tap density is 4.5 g / cm3. Figure 2 . 3 . Example 3

[0032] The silver palladium alloy powder high-temperature heat treatment method disclosed in this embodiment includes the following steps.

[0033] Step one, 50g of 1000nm ultra-fine silver palladium powder is poured into a hydrothermal reactor 200mL of deionized water and stirred, 80 times the mass of the ultra-fine silver palladium powder of polyvinylpyrrolidone is added as a dispersant, and after the silver palladium powder is completely dispersed in the water, 10 times the mass of the ultra-fine silver palladium powder of tannic acid is added as a coating agent and stirring is continued.

[0034] Step two, the hydrothermal reactor is heated to 220°C and heat preserved for 1h to perform hydrothermal coating, and stirring is continuously performed during the process. After the coating is completed, the solution in the hydrothermal reactor is centrifuged to separate the solid and liquid phases, washed, dried, and crushed to obtain the coated silver palladium alloy powder.

[0035] Step three, the coated silver palladium alloy powder and 30 times the mass of the ultra-fine silver palladium powder of aldehyde are uniformly mixed.

[0036] Step four, the mixture of silver palladium alloy powder obtained in step three and aldehyde is placed in a muffle furnace and heated to 700°C, and a high-temperature heat-treated mixture of silver palladium alloy powder and aldehyde is obtained after 1h of heat preservation. Finally, the high-temperature heat-treated silver palladium alloy powder is obtained after washing, drying, and crushing. Through SEM analysis as shown in FIG. 1, the particle size distribution D50 of the silver palladium alloy powder is 2.0 μm, and the tap density is 5.0 g / cm3. Figure 3 . 3 . Example 4

[0037] The silver palladium alloy powder high-temperature heat treatment method disclosed in this embodiment includes the following steps.

[0038] Step one, 50g of 2000nm ultra-fine silver palladium powder is poured into a hydrothermal reactor 200mL of deionized water and stirred, 100 times the mass of the ultra-fine silver palladium powder of gum arabic is added as a dispersant, and after the silver palladium powder is completely dispersed in the water, 20 times the mass of the ultra-fine silver palladium powder of tannic acid is added as a coating agent and stirring is continued.

[0039] Step two, the hydrothermal reactor is heated to 300 DEG C, and hydrothermal coating is carried out for 2h, and the solution in the hydrothermal reactor is centrifuged to separate solid and liquid phases, washed, dried, and crushed to obtain the coated silver-palladium alloy powder.

[0040] Step three, the coated silver-palladium alloy powder and 20 times the mass of anhydrous sodium sulfate are uniformly mixed.

[0041] Step four, the mixture of the silver-palladium alloy powder and anhydrous sodium sulfate obtained in step three is placed in a muffle furnace and heated to 900 DEG C, and a high-temperature heat-treated silver-palladium alloy powder and anhydrous sodium sulfate mixture is obtained after 0.5h of heat preservation, and finally, the mixture is washed, dried, and crushed to obtain the high-temperature heat-treated silver-palladium alloy powder. Figure 4 As shown in the SEM analysis, the particle size distribution D50 of the silver-palladium alloy powder is 1.5um, and the tap density is 6.0g / cm 3 .

[0042] The technical content and features of the present application are as shown above, but the protection scope of the present application should not be limited to the content expressed by the examples, but should include various substitutions and modifications without departing from the present application, and is covered by the claims of the present patent application.

Claims

1. A high-temperature heat treatment method for silver-palladium alloy powder, characterized in that: Includes the following steps: Step 1: Weigh out ultrafine silver-palladium powder with a particle size distribution D50 of 300-2000 nm and deionized water, pour them into a hydrothermal reactor and stir. Then add 10-100 times the mass of the ultrafine silver-palladium powder as a dispersant, such as polyvinylpyrrolidone, polyethylene glycol or gum arabic. After the silver-palladium powder is completely dispersed in the water, add 3.3-20 times the mass of the ultrafine silver-palladium powder as a coating agent and continue stirring. Step 2: Heat the hydrothermal reactor to 120-300℃ and keep it at that temperature for 1-24 hours for hydrothermal coating. Stir continuously during the process. After coating, centrifuge the solution to separate the solid and liquid phases, wash, dry, and crush to obtain coated silver-palladium alloy powder. Step 3: Mix the coated silver-palladium alloy powder and ultrafine silver-palladium powder with 1 to 30 times the mass of sodium chloride, anhydrous sodium sulfate or aldehydes until homogeneous. Step four: Place the mixture in a muffle furnace and heat it to 300–900℃, holding it at that temperature for 0.5–4 hours. The resulting high-temperature heat-treated mixture is then washed, dried, and crushed to obtain a particle size distribution D50 of 1.5–2.5 μm and a tap density of 4.2–6.0 g / cm³. 3 Silver-palladium alloy powder.

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