High-temperature heat treatment method for silver-palladium alloy powder

Abstract

The invention discloses a high-temperature heat treatment method of silver-palladium alloy powder, which comprises the following steps: weighing superfine silver-palladium powder, pouring into deionized water for hydrothermal reaction, preparing a dispersing agent and a coating agent solution, adding into a hydrothermal reaction kettle, heating the hydrothermal reaction kettle, keeping the temperature, and performing hydrothermal coating; the preparation method comprises the following steps: preparing a hydrothermal reaction kettle, centrifugally separating solid and liquid phases from a solution in the hydrothermal reaction kettle, washing, drying and crushing to obtain coated silver-palladium alloy powder, uniformly mixing the silver-palladium alloy powder and salt according to a required proportion, heating to a required temperature in a muffle furnace, and preserving heat to obtain a mixture of the high-temperature heat-treated silver-palladium alloy powder and the salt; and finally, washing, drying and crushing to obtain the high-temperature heat treatment silver-palladium alloy powder. According to the method, the silver-palladium alloy powder with the diameter of 1.5-2.5 microns and the tap density of 4.2-6.0 g / cm < 3 > can be prepared by changing the variety and concentration of the coating agent, the hydrothermal reaction temperature and time, the variety and proportion of salt and the heat treatment temperature and time.

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal powder material preparation, and relates to a high-temperature heat treatment method for silver-palladium alloy powder. Background Art

[0002] Silver has the highest electrical and thermal conductivity of all metals, and is the cheapest of the precious metals. It also has good processability. Palladium can overcome the two major defects of silver as a conductive material in the microelectronics industry: silver ion migration and poor resistance to solder erosion. It has greatly improved the reliability of microelectronic devices and has become a highly regarded conductive functional filler for electronic pastes. The superiority of silver-palladium alloy parameters such as particle size, morphology, particle size distribution, tap density and surface state will have an important impact on performance.

[0003] At present, the preparation methods of silver-palladium alloy include physical method and chemical method. The chemical method is the main method used for large-scale production due to its low production cost and easy control. However, the particle size of silver-palladium alloy powder prepared by the chemical method is 300-2000nm and the tap density is 3.0g / cm 3 There are deficiencies in surface roughness, low tap density, and alloying. Summary of the invention

[0004] The present invention solves the above problems and aims at the shortcomings of the existing silver-palladium alloy heat treatment technology, and provides a high-temperature heat treatment method for silver-palladium alloy powder to obtain silver-palladium alloy powder with smooth surface, good alloying and high tap density.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a high-temperature heat treatment method for silver-palladium alloy powder, comprising the following steps: Step 1, weighing 50g of ultrafine silver palladium powder with a particle size distribution D50 of 300-2000nm and 200mL of deionized water, pouring them into a hydrothermal reactor and stirring, then adding a dispersant 10-100 times the mass of the ultrafine silver palladium powder, and after the silver palladium powder is completely dispersed in the water, adding a coating agent 3.3-20 times the mass of the ultrafine silver palladium powder and continuing to stir; Step 2, heating the hydrothermal reactor to 120-300° C. and keeping the temperature for 1-24 hours for hydrothermal coating, stirring continuously during the process, and after the coating is completed, centrifuging the solution in the hydrothermal reactor to separate the solid and liquid phases, washing, drying, and crushing to obtain the coated silver-palladium alloy powder; Step 3, uniformly mixing the coated silver-palladium alloy powder and salt with a mass of 1 to 30 times that of the ultrafine silver-palladium powder; Step 4: Place the mixture of the obtained silver-palladium alloy powder and salt in a muffle furnace and heat it to 300-900°C for 0.5-4h. The obtained high-temperature heat-treated mixture is washed, dried, and crushed to obtain a particle size distribution D50 of 1.5-2.5μm and a tap density of 4.2-6.0g / cm 3 Silver-palladium alloy powder.

[0006] The high-temperature heat treatment method for silver-palladium alloy powder comprises a dispersant of polyvinyl pyrrolidone, polyethylene glycol or gum arabic.

[0007] In the high-temperature heat treatment method for silver-palladium alloy powder, the coating agent is glucose or tannic acid.

[0008] In the high-temperature heat treatment method for silver-palladium alloy powder, the salt is a water-soluble inorganic salt such as sodium chloride and anhydrous sodium sulfate, or an organic salt such as aldehydes.

[0009] The advantages and positive effects of the present invention are as follows: 1. The method of the present invention controls the particle size of the silver-palladium alloy powder and improves the agglomeration effect of the silver-palladium alloy powder at high temperature by controlling and changing the coating agent and its dosage, hydrothermal temperature and time, and the type and proportion of the salt.

[0010] 2. The method of the present invention achieves the goals of reducing the activity of silver-palladium powder, increasing the degree of alloying, and increasing the tap density by changing the heat treatment temperature and time.

[0011] 3. After high temperature heat treatment of ultrafine silver palladium powder with a particle size distribution D50 of 300-2000nm by this patented method, the particle size can reach 1.5-2.5μm and the tap density can reach 4.2-6.0g / cm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 1 of the present invention; Figure 2 This is a SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 2 of the present invention; Figure 3 This is a SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 3 of the present invention; Figure 4 This is a SEM image of the silver-palladium alloy powder after high-temperature heat treatment in Example 4 of the present invention. DETAILED DESCRIPTION

[0013] The present invention is specifically described below through examples and drawings to further illustrate the present invention, which should not be construed as limiting the protection scope of the present invention. Example 1

[0014] The present embodiment discloses a high-temperature heat treatment method for silver-palladium alloy powder, which includes the following steps.

[0015] Step 1: weigh 50 g of ultrafine silver palladium powder with a particle size of 400 nm, pour it into 200 mL of deionized water in a hydrothermal reactor and stir, add polyethylene glycol 10 times the mass of the ultrafine silver palladium powder as a dispersant, and after the silver palladium powder is completely dispersed in the water, add glucose 3.3 times the mass of the ultrafine silver palladium powder as a coating agent and continue stirring.

[0016] Step 2, heating the hydrothermal reactor to 120°C and keeping it warm for 24 hours for hydrothermal coating, stirring continuously during the process. After the coating is completed, centrifuging the solution in the hydrothermal reactor to separate the solid and liquid phases, washing, drying and crushing to obtain the coated silver-palladium alloy powder.

[0017] Step 3: Evenly mix the coated silver-palladium alloy powder and sodium chloride with a mass that is 1 times that of the ultrafine silver-palladium powder.

[0018] Step 4: Place the mixture of silver-palladium alloy powder and sodium chloride obtained in step 3 in a muffle furnace and heat it to 300°C. Keep it warm for 4 hours to obtain a mixture of high-temperature heat-treated silver-palladium alloy powder and sodium chloride. Finally, wash, dry and crush to obtain high-temperature heat-treated silver-palladium alloy powder. Figure 1 The analysis shows that the particle size distribution D50 of the silver-palladium alloy powder is 2.5 μm and the tap density is 4.2 g / cm 3 . Example 2

[0019] The present embodiment discloses a high-temperature heat treatment method for silver-palladium alloy powder, which includes the following steps.

[0020] Step 1, weigh 50g of ultrafine silver palladium powder with a particle size of 300nm, pour it into 200mL of deionized water in a hydrothermal reactor and stir, add 80 times the mass of polyvinyl pyrrolidone of the ultrafine silver palladium powder as a dispersant, and after the silver palladium powder is completely dispersed in the water, add 5 times the mass of glucose of the ultrafine silver palladium powder as a coating agent and continue stirring.

[0021] Step 2: Heat the hydrothermal reactor to 200° C. and keep it warm for 10 hours for hydrothermal coating with continuous stirring. 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.

[0022] Step 3: Evenly mix the coated silver-palladium alloy powder and anhydrous sodium sulfate which is 5 times the mass of the ultrafine silver-palladium powder.

[0023] Step 4: Place the mixture of silver-palladium alloy powder and anhydrous sodium sulfate obtained in step 3 in a muffle furnace and heat it to 500°C. Keep it warm for 3 hours to obtain a mixture of high-temperature heat-treated silver-palladium alloy powder and anhydrous sodium sulfate. Finally, wash, dry and crush to obtain high-temperature heat-treated silver-palladium alloy powder. Figure 2 The analysis shows that the particle size distribution D50 of the silver-palladium alloy powder is 2.0 μm and the tap density is 4.5 g / cm 3 . Example 3

[0024] The present embodiment discloses a high-temperature heat treatment method for silver-palladium alloy powder, which includes the following steps.

[0025] Step 1, weigh 50g of ultrafine silver palladium powder with a particle size of 1000nm, pour it into 200mL of deionized water in a hydrothermal reactor and stir, add 80 times the mass of polyvinyl pyrrolidone of the ultrafine silver palladium powder as a dispersant, and after the silver palladium powder is completely dispersed in the water, add 10 times the mass of tannic acid of the ultrafine silver palladium powder as a coating agent and continue stirring.

[0026] Step 2, heating the hydrothermal reactor to 220°C and keeping it warm for 1 hour for hydrothermal coating, stirring continuously during the process. After the coating is completed, centrifuging the solution in the hydrothermal reactor to separate the solid and liquid phases, washing, drying and crushing to obtain the coated silver-palladium alloy powder.

[0027] Step 3: Evenly mix the coated silver-palladium alloy powder and aldehydes which are 30 times the mass of the ultrafine silver-palladium powder.

[0028] Step 4: Place the mixture of silver-palladium alloy powder and aldehyde obtained in step 3 in a muffle furnace and heat it to 700°C. Keep it warm for 1 hour to obtain a mixture of high-temperature heat-treated silver-palladium alloy powder and aldehyde. Finally, wash, dry and crush to obtain high-temperature heat-treated silver-palladium alloy powder. Figure 3 The analysis shows that the particle size distribution D50 of the silver-palladium alloy powder is 2.0 μm and the tap density is 5.0 g / cm 3 . Example 4

[0029] The present embodiment discloses a high-temperature heat treatment method for silver-palladium alloy powder, which includes the following steps.

[0030] Step 1, weigh 50g of ultrafine silver palladium powder with a particle size of 2000nm, pour it into 200mL of deionized water in a hydrothermal reactor and stir, add 100 times the mass of gum arabic as a dispersant, and after the silver palladium powder is completely dispersed in the water, add 20 times the mass of tannic acid as a coating agent and continue stirring.

[0031] Step 2, heating the hydrothermal reactor to 300°C and keeping it warm for 2 hours for hydrothermal coating, stirring continuously during the process. After the coating is completed, centrifuging the solution in the hydrothermal reactor to separate the solid and liquid phases, washing, drying and crushing to obtain the coated silver-palladium alloy powder.

[0032] Step 3: Evenly mix the coated silver-palladium alloy powder and anhydrous sodium sulfate which is 20 times the mass of the ultrafine silver-palladium powder.

[0033] Step 4: Place the mixture of silver-palladium alloy powder and anhydrous sodium sulfate obtained in step 3 in a muffle furnace and heat it to 900°C. Keep it warm for 0.5h to obtain a mixture of high-temperature heat-treated silver-palladium alloy powder and anhydrous sodium sulfate. Finally, wash, dry and crush to obtain high-temperature heat-treated silver-palladium alloy powder. Figure 4 The analysis shows that the particle size distribution D50 of the silver-palladium alloy powder is 1.5 μm and the tap density is 6.0 g / cm 3 .

[0034] The technical contents and features of the present invention are as shown above, but the protection scope of the present invention should not be limited to the contents described in the embodiments, but should include various replacements and modifications that do not deviate from the present invention and are covered by the claims of this patent application.

Claims

1. A high temperature heat treatment method for silver-palladium alloy powder, characterized in that: The following steps are included Step 1, weighing ultrafine silver palladium powder with a particle size distribution D50 of 300 to 2000 nm and deionized water, pouring them into a hydrothermal reactor and stirring, then adding a dispersant in an amount of 10 to 100 times the mass of the ultrafine silver palladium powder, and after the silver palladium powder is completely dispersed in the water, adding a coating agent in an amount of 3.3 to 20 times the mass of the ultrafine silver palladium powder and continuing to stir; Step 2, heating the hydrothermal reaction kettle to 120-300° C. and keeping the temperature for 1-24 hours for hydrothermal coating, stirring continuously during the process, and after the coating is completed, centrifuging the solution to separate the solid and liquid phases, washing, drying, and crushing to obtain the coated silver-palladium alloy powder; Step 3, uniformly mixing the coated silver-palladium alloy powder and salt with a mass of 1 to 30 times that of the ultrafine silver-palladium powder; Step 4: Place the mixture in a muffle furnace and heat it to 300-900°C for 0.5-4h. The obtained high temperature heat treated mixture is washed, dried and crushed to obtain a particle size distribution D50 of 1.5-2.5μm and a tap density of 4.2-6.0g / cm 3 Silver-palladium alloy powder.

2. The high temperature heat treatment method of a silver-palladium alloy powder according to claim 1, characterized in that: The dispersant is polyvinyl pyrrolidone, polyethylene glycol or gum arabic.

3. A high temperature heat treatment method for silver-palladium alloy powder according to claim 1 or 2, characterized in that: The coating agent is glucose or tannic acid.

4. The high temperature heat treatment method of a silver-palladium alloy powder according to claim 3, characterized in that: The salt is sodium chloride, anhydrous sodium sulfate or aldehydes.

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