Preparation method of low-activity silver powder

Abstract

The invention discloses a preparation method of low-activity silver powder, which comprises the following steps: weighing a proper amount of dispersing agent, dissolving in deionized water to prepare a reaction base solution, uniformly mixing silver nitrate and deionized water to obtain an oxidizing agent solution, dissolving Vc in deionized water to obtain a reducing agent solution, dropwise adding the oxidizing agent solution and the reducing agent solution into the reaction base solution together, and stirring to obtain the low-activity silver powder. The preparation method comprises the following steps: adding an organic solvent into a reaction kettle until complete reaction, coating an organic matter with an obtained solution through a hydrothermal method, then centrifuging, washing and drying, crushing and dispersing the coated silver powder, and putting into a muffle furnace for high-temperature heat treatment to obtain the low-activity silver powder. The low-activity silver powder prepared through the method has the advantage of being low in activity, can be used for large-scale production of silver-palladium alloy and is applied to various fields.

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal powder material preparation, and relates to a method for preparing low-activity silver powder. Background Art

[0002] Low Temperature Co-fired Ceramics (LTCC) technology is a process that uses ceramic materials and conductive materials to form a multilayer structure at a relatively low temperature (generally no more than 850°C). LTCC technology is widely used in communications, automotive electronics, medical equipment and other fields due to its high integration, good thermal stability and ability to adapt to high-frequency circuits.

[0003] In LTCC applications, conductive materials must meet requirements such as high conductivity, low sintering temperature, and good compatibility. Silver (Ag) is the main choice due to its excellent conductive properties, but traditional silver powder may be too active at high temperatures, resulting in excessive sintering and loss of structural stability.

[0004] Low-activity silver powder is a silver powder that exhibits lower chemical activity and stronger thermal stability during the sintering process. Compared with traditional silver powder, low-activity silver powder can better maintain its structural integrity and electrical properties under high temperature conditions, avoiding the performance degradation of the conductive layer due to excessive sintering. The advantages of low-activity silver powder are: 1. Controlling the sintering process. The lower reactivity of low-activity silver powder makes it easier to control the sintering temperature and time during the co-firing process, thereby effectively reducing energy consumption. 2. Improving electrical properties. Since low-activity silver powder is not easy to form large particles at high temperatures, it can maintain a good microstructure and density, thereby improving the conductivity and stability of the final conductive layer. 3. Reducing oxidation risk. Low-activity silver powder has good oxidation resistance, which reduces oxidation losses during high-temperature sintering and improves the long-term stability and reliability of the material.

[0005] As electronic devices develop towards miniaturization and high integration, the importance of silver powder in LTCC applications is becoming increasingly prominent. Its excellent properties make it a key conductive material in future electronic components, especially in high-frequency and complex structure circuit design, which can meet the strict requirements of modern technology for performance and reliability. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for preparing low-activity silver powder in view of the shortcomings of the existing silver powder preparation technology.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing low-activity silver powder, comprising the following steps: Step 1: weigh 40-60 g of dispersant in a reaction kettle and fully dissolve it in 1 L of deionized water as a reaction base liquid; Step 2: weigh 4 to 20 times the mass of the dispersant and silver nitrate and 500 to 1000 mL of deionized water, pour them into a beaker and stir evenly as an oxidant solution; weigh 200 g of Vc and dissolve it in 500 to 1000 mL of deionized water as a reducing agent solution; Step 3, using a peristaltic pump to simultaneously drip an oxidant solution and a reductant solution with a molar ratio of 0.5 to 2:1 into the reaction base solution until the reaction is complete; Step 4, centrifuge the obtained reaction solution, wash it with deionized water several times, and finally adjust the volume to 200 mL, pour it into a hydrothermal reactor, add 10 mL of polyvinyl alcohol solution, stir for 30 minutes, add 10 mL of glucose solution, and then pour it into the hydrothermal reactor for hydrothermal coating; Step 5, centrifuging the coated solution, washing several times, and drying to obtain silver powder, breaking and dispersing the silver powder, heating it to 500-700° C. in a muffle furnace, and keeping it warm for 1-2 hours to obtain the silver powder after high-temperature heat treatment.

[0008] Furthermore, in the step 1, the dispersant is polyvinyl pyrrolidone K60, methyl cellulose or gum arabic.

[0009] Furthermore, in step three, the dropping speed is 10 to 30 L / min.

[0010] Furthermore, in step 4, the hydrothermal reaction temperature is 150°C to 250°C, and the insulation time is 10 to 14 hours. The advantages and positive effects of the present invention are as follows: 1. The method of the present invention improves the agglomeration effect of silver powder at high temperature by controlling and changing the addition amount of the coating agent glucose solution;

[0011] 2. The method of the present invention achieves the goals of making the surface of the silver powder smooth and reducing its activity by changing the temperature of the muffle furnace at 500-700°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a SEM image of the low-activity silver powder prepared in Example 1; Figure 2 This is a SEM image of the low-activity silver powder prepared in Example 2; Figure 3 This is the SEM image of the low-activity silver powder prepared in Example 3. 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] This embodiment discloses a method for preparing low-activity silver powder, and the steps are as follows.

[0015] Step 1: weigh 50 g of polyvinyl pyrrolidone K60 as a dispersant in a reaction kettle and fully dissolve it in 1 L of deionized water as a reaction base liquid.

[0016] Step 2: weigh the silver nitrate solution so that the amount of dispersant added is 5-25% of the mass of the silver nitrate, weigh 1000 mL of deionized water and stir until completely dissolved as the oxidant solution, weigh 200 g of Vc and dissolve it in 1000 mL of water as the reducing agent solution.

[0017] Step 3: Use a peristaltic pump to simultaneously drip an oxidant and a reductant in a molar ratio of 0.5:1 at a dripping rate of 20 mL / min until the reaction is completed.

[0018] Step 4: After the reaction is completed, the solution is centrifuged and washed with water for several times, and finally the volume is adjusted to 200 mL, 10 mL of polyvinyl alcohol solution is added to the solution, and 10 mL of glucose solution is added after stirring for 30 minutes. Then, the solution is poured into a hydrothermal reactor and hydrothermally coated at 200°C for 12 hours.

[0019] Step 5: Centrifuge the coated solution, wash it several times to obtain silver powder, dry it, disperse it, put it into a muffle furnace and heat it to 500°C, and keep it warm for 1 hour to obtain low-activity silver powder. Figure 1 shown. Example 2

[0020] This embodiment discloses a method for preparing low-activity silver powder, and the steps are as follows.

[0021] Step 1: weigh 60 g of methyl cellulose as a dispersant in a reaction kettle and fully dissolve it in 1 L of deionized water as a reaction base liquid.

[0022] Step 2: weigh the silver nitrate solution so that the amount of dispersant added is 5-25% of the mass of the silver nitrate, weigh 800 mL of deionized water and stir until completely dissolved as the oxidant solution, weigh 200 g of Vc and dissolve it in 800 mL of water as the reducing agent solution.

[0023] Step 3: Use a peristaltic pump to simultaneously drip the oxidant and the reductant in a molar ratio of 1:1 at a dripping speed of 10 mL / min until the reaction is completed.

[0024] Step 4: After the reaction solution is centrifuged, it is washed with water several times and finally the volume is adjusted to 200 mL. 10 mL of polyvinyl alcohol solution is added to the solution. After stirring for 30 min, 10 mL of glucose solution is added. Then, the solution is poured into a hydrothermal reactor and hydrothermally coated at 150 ° C for 14 h.

[0025] Step 5: Centrifuge the coated solution, wash it several times to obtain silver powder, dry it, disperse it, put it into a muffle furnace and heat it to 600°C, and keep it warm for 1.5 hours to obtain low-activity silver powder. Figure 2 shown. Example 3

[0026] This embodiment discloses a method for preparing low-activity silver powder, and the steps are as follows.

[0027] Step 1: weigh 40 g of gum arabic as a dispersant in a reactor and fully dissolve it in 1 L of deionized water as a reaction base liquid.

[0028] Step 2: weigh the silver nitrate solution so that the amount of dispersant added is 5-25% of the mass of the silver nitrate, weigh 500 mL of deionized water and stir until completely dissolved as the oxidant solution, weigh 200 g of Vc and dissolve it in 500 mL of water as the reducing agent solution.

[0029] Step 3: Use a peristaltic pump to simultaneously drip the oxidant and the reductant in a molar ratio of 2:1 at a dripping speed of 30 mL / min until the reaction is completed.

[0030] Step 4: After the reaction solution is centrifuged, it is washed with water several times, and finally the volume is adjusted to 200 mL. 10 mL of polyvinyl alcohol solution is added to the solution, and after stirring for 30 min, 10 mL of glucose solution is added. Then, it is poured into a hydrothermal reactor and hydrothermally coated at 250°C for 10 h.

[0031] Step 5: Centrifuge the coated solution, wash it several times to obtain silver powder, dry it, disperse it, put it into a muffle furnace and heat it to 700°C, and keep it warm for 2 hours to obtain low-activity silver powder. Figure 3 shown.

[0032] 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 method for preparing low-activity silver powder, characterized in that: The following steps are included Step 1: weigh 40-60 g of dispersant and dissolve it in 1 L of deionized water as the reaction base solution; Step 2: weigh 4 to 20 times the mass of the dispersant and silver nitrate and 500 to 1000 mL of deionized water, pour them into a beaker and stir evenly as an oxidant solution; weigh 200 g of Vc and dissolve it in 500 to 1000 mL of deionized water as a reducing agent solution; Step 3, using a peristaltic pump to simultaneously drip an oxidant solution and a reductant solution with a molar ratio of 0.5 to 2:1 into the reaction base solution until the reaction is complete; Step 4, centrifuging the obtained reaction solution, washing it with deionized water, pouring it into a hydrothermal reactor, adding the polyvinyl alcohol solution, stirring it, adding the glucose solution, and then pouring it into the hydrothermal reactor for hydrothermal coating; Step 5, centrifuging, washing and drying the coated solution to obtain silver powder, crushing and dispersing the silver powder, heating it to 500-700° C. in a muffle furnace, and keeping it warm for 1-2 hours to obtain low-activity silver powder.

2. The method for preparing low-activity silver powder according to claim 1, characterized in that: In the step 1, the dispersant is polyvinyl pyrrolidone K60, methyl cellulose or gum arabic.

3. The method for preparing low-activity silver powder according to claim 1 or 2, characterized in that: The dropping speed in the step 3 is 10 to 30 L / min.

4. The method for preparing low-activity silver powder according to claim 3, characterized in that: In the step 4, the hydrothermal reaction temperature is 150°C to 250°C, and the insulation time is 10 to 14 hours.

Images