A method for preparing low-activity silver powder

Abstract

The application discloses a preparation method of low-activity silver powder, and comprises the following steps: weighing a proper amount of dispersing agent, dissolving the dispersing agent in deionized water to obtain 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, dropping the oxidizing agent solution and the reducing agent solution into the reaction base solution until complete reaction, coating the obtained solution with organic matters through a hydrothermal method, and then centrifuging, washing, drying, crushing and dispersing the coated silver powder, and finally putting the silver powder into a muffle furnace for high-temperature heat treatment to obtain the low-activity silver powder. The low-activity silver powder prepared by the method has the characteristics of low activity, can be used for large-scale production of silver-palladium alloy, and can be applied to various fields.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of noble metal powder material preparation, and relates to a preparation method of low-activity silver powder. BACKGROUND

[0002] Low Temperature Co-fired Ceramics (LTCC) technology is a process of co-firing ceramic materials with conductive materials to form a multi-layer structure at a relatively low temperature (generally not exceeding 850℃). LTCC technology is widely used in communication, automotive electronics, medical devices and other fields due to its high integration, good thermal stability and ability to adapt to high-frequency circuits.

[0003] In the application of LTCC, the conductive material must meet the requirements of high conductivity, low sintering temperature, good compatibility, etc. Silver (Ag) is the main choice due to its excellent electrical conductivity, but traditional silver powder may have excessive activity at high temperatures, leading to excessive sintering and loss of structural stability.

[0004] Low-activity silver powder is a type of silver powder that exhibits low chemical activity and strong thermal stability during the sintering process. Compared to traditional silver powder, low-activity silver powder can better maintain its structural integrity and electrical properties under high-temperature conditions, avoiding 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 co-firing, effectively reducing energy consumption. 2. Improving electrical properties, as low-activity silver powder is less likely to form large particles at high temperatures, it can maintain 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, reducing oxidation loss during high-temperature sintering, improving the long-term stability and reliability of the material.

[0005] With the development of electronic devices towards miniaturization and high integration, the importance of silver powder in LTCC applications is increasingly prominent. Its excellent properties make it a key conductive material in future electronic components, especially in high-frequency and complex circuit designs, meeting the strict requirements of modern technology for performance and reliability. SUMMARY

[0006] To solve the above problems, the present application provides a preparation method of low-activity silver powder to overcome the shortcomings of existing silver powder preparation technology.

[0007] The technical solution adopted by the application to solve the technical problems is: a preparation method of low-activity silver powder, comprising the following steps:

[0008] Step one, 40-60g dispersant is weighed in a reaction kettle and dissolved in 1L deionized water as a reaction bottom solution;

[0009] Step two, silver nitrate with 4-20 times the mass of the dispersant and 500-1000mL deionized water are weighed into a beaker and stirred uniformly as an oxidant solution, and 200g Vc is dissolved in 500-1000mL deionized water as a reducing agent solution;

[0010] Step three, the oxidant solution and the reducing agent solution with a molar ratio of 0.5-2:1 are simultaneously dropped into the reaction bottom solution by using a peristaltic pump until the reaction is completed;

[0011] Step four, the obtained reaction solution is centrifuged and washed several times with deionized water, finally constant volume to 200mL, and poured into a hydrothermal reaction kettle, 10mL polyvinyl alcohol solution is added, stirred for 30min, then 10mL glucose solution is added, and then poured into a hydrothermal reaction kettle for hydrothermal coating;

[0012] Step five, the coated solution is centrifuged, washed several times, and dried to obtain silver powder, the silver powder is crushed and dispersed, heated to 500-700℃ in a muffle furnace, and kept for 1-2h to obtain high-temperature heat-treated silver powder.

[0013] Further, the dispersant in step one is polyvinylpyrrolidone K60, methyl cellulose or gum arabic.

[0014] Further, the dropping speed in step three is 10-30L / min.

[0015] Further, the hydrothermal reaction temperature in step four is 150-250℃, and the holding time is 10-14h

[0016] The application has the following advantages and positive effects:

[0017] 1. The method of the application improves the effect of silver powder agglomeration at high temperature by controlling the addition amount of the coating agent glucose solution;

[0018] 2. The method of the application changes the muffle furnace temperature at 500-700℃ to achieve the goal of smooth surface of silver powder and reduced activity. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 SEM image of low-activity silver powder prepared for Example 1;

[0020] Figure 2 SEM image of low-activity silver powder prepared for Example 2;

[0021] Figure 3 SEM image of low-activity silver powder prepared for Example 3. Detailed Implementation

[0022] The present invention will be described in detail below with reference to embodiments and accompanying drawings, and will be further explained in a manner that should not be construed as limiting the scope of protection of the present invention. Example 1

[0023] This embodiment discloses a method for preparing low-activity silver powder, the steps of which are as follows.

[0024] Step 1: Weigh 50g of polyvinylpyrrolidone K60 into the reaction vessel and dissolve it completely in 1L of deionized water to prepare the reaction base solution.

[0025] Step 2: Weigh out silver nitrate solution, and add dispersant at 5-25% of the mass of silver nitrate. Measure 1000 mL of deionized water and stir until completely dissolved to prepare the oxidizing agent solution. Weigh out 200 g of vitamin C and dissolve it in 1000 mL of water to prepare the reducing agent solution.

[0026] Step 3: Using a peristaltic pump, simultaneously add an oxidant and a reducing agent with a molar ratio of 0.5:1 at a dropping rate of 20 mL / min until the reaction is complete.

[0027] Step four: After centrifuging the reacted solution, wash it several times with water, and finally bring the volume to 200 mL. Add 10 mL of polyvinyl alcohol solution to the solution, stir for 30 min, and then add 10 mL of glucose solution. Then pour it into a hydrothermal reactor and hydrothermally coat it at 200 °C for 12 h.

[0028] Step 5: After centrifuging and washing the coated solution several times to obtain silver powder, dry it, disperse it, and then heat it in a muffle furnace to 500℃ and hold it at that temperature for 1 hour to obtain low-activity silver powder. The silver powder is then analyzed by SEM electron microscopy. Figure 1 As shown. Example 2

[0029] This embodiment discloses a method for preparing low-activity silver powder, the steps of which are as follows.

[0030] Step 1: Weigh 60g of methylcellulose into the reaction vessel and dissolve it completely in 1L of deionized water to prepare the reaction base solution.

[0031] Step 2: Weigh out silver nitrate solution, and add dispersant at 5-25% of the mass of silver nitrate. Measure 800 mL of deionized water and stir until completely dissolved to prepare the oxidizing agent solution. Weigh out 200 g of vitamin C and dissolve it in 800 mL of water to prepare the reducing agent solution.

[0032] Step 3: Using a peristaltic pump, simultaneously add oxidant and reducing agent in a molar ratio of 1:1 at a dropping rate of 10 mL / min until the reaction is complete.

[0033] Step four, the reaction solution is centrifuged and washed with water several times, and finally the volume is made to 200 mL. 10 mL of polyvinyl alcohol solution is added to the solution, stirred for 30 min, and then 10 mL of glucose solution is added. Subsequently, pour into the hydrothermal reaction kettle, hydrothermal coating at 150℃ for 14h.

[0034] Step five, the coated solution is centrifuged and washed several times to obtain silver powder, which is dried and dispersed and then heated to 600℃ in a muffle furnace for 1.5h to obtain low-activity silver powder. The SEM image is shown in Figure 2 . Example 3

[0035] The disclosed preparation method of the low-activity silver powder is as follows.

[0036] Step one, weigh 40g of gum arabic as a dispersant and dissolve it in 1L of deionized water in a reaction kettle as a reaction bottom solution.

[0037] Step two, weigh the silver nitrate solution, so that the amount of dispersant added is 5-25% of the mass of silver nitrate. Measure 500mL of deionized water and stir until completely dissolved as an oxidizing agent solution. Weigh 200g of Vc and dissolve it in 500mL of water as a reducing agent solution.

[0038] Step three, use a peristaltic pump to add the oxidizing agent and reducing agent with a molar ratio of 2:1 at the same time, and the dropwise adding speed is 30mL / min. After the reaction is completed.

[0039] Step four, the reaction solution is centrifuged and washed with water several times, and finally the volume is made to 200 mL. 10 mL of polyvinyl alcohol solution is added to the solution, stirred for 30 min, and then 10 mL of glucose solution is added. Subsequently, pour into the hydrothermal reaction kettle, hydrothermal coating at 250℃ for 10h.

[0040] Step five, the coated solution is centrifuged and washed several times to obtain silver powder, which is dried and dispersed and then heated to 700℃ in a muffle furnace for 2h to obtain low-activity silver powder. The SEM image is shown in Figure 3 .

[0041] 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 in the examples, but should include various alternatives and modifications without departing from the present application, and is covered by the claims of the present patent application.

Claims

1. A method for producing a low-activity silver powder, characterized by: Comprising the following steps Step one, take 40-60g methyl cellulose as dispersant dissolved in 1L deionized water as the reaction bottom; Step two, take the dispersant mass 4-20 times of silver nitrate and 500-1000mL deionized water into a beaker and stir evenly as the oxidant solution, take 200g Vc dissolved in 500-1000mL deionized water as the reducing agent solution; Step three, use peristaltic pump to drop the oxidant solution and reducing agent solution with molar ratio of 0.5-2:1 into the reaction bottom at the same time, the drop speed is 10-30L / min, until the complete reaction; Step four, centrifuge the obtained reaction solution, wash several times with deionized water, finally constant volume to 200mL, add 10mL polyvinyl alcohol solution, stir for 30min, then add 10mL glucose solution, then pour into the hydrothermal reaction kettle for hydrothermal coating, the hydrothermal reaction temperature is 150-250℃, the holding time is 10-14h; Step five, centrifuge, wash and dry the coated solution to obtain silver powder, crush and disperse the silver powder, heat to 500-700℃ in the muffle furnace, hold for 1-2h to obtain low activity silver powder.

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