Preparation method of low-resistance flaky silver-palladium alloy powder and conductive paste

Abstract

The application provides a preparation method of low-resistance flaky silver-palladium alloy powder and conductive paste, and belongs to the field of preparation of precious metal powder materials. The preparation method of low-resistance flaky silver-palladium alloy powder comprises the following steps: (1) mixing a silver salt solution, a palladium salt solution and a reducing agent solution to perform a reduction reaction, so as to obtain silver-palladium alloy powder; (2) mixing the silver-palladium alloy powder, a dispersion liquid and a ball-milling dispersant, and then performing ball-milling, so as to obtain flaky silver-palladium alloy powder; the milling balls used in the ball-milling include one or more of steel balls, zirconium dioxide balls and agate balls. The flaky silver-palladium alloy powder is prepared by adopting the mode of "alloying first and then ball-milling", the two key links of "alloying" and "flaky" can be independently optimized, the uniformity and the controllability of the morphology of the powder are improved at the atomic level, the prepared flaky silver-palladium alloy powder has good dispersibility and a smooth surface, and has a resistance superior to that of spherical alloy powder, spherical mixed powder and flaky mixed powder.

Description

Technical Field

[0001] This invention relates to the field of precious metal powder material preparation, specifically to a method for preparing low-resistivity flake silver-palladium alloy powder and a conductive slurry. Background Technology

[0002] While silver, the most widely used metallic material in electrode circuits, is relatively inexpensive and has good conductivity, it is only suitable for low-end or simple applications where cost is extremely sensitive and the operating environment is very dry, without electric fields, and without corrosive atmospheres (such as some membrane switches and low-temperature polymer conductive silver pastes). Compared to pure silver powder, silver-palladium powder (including silver-palladium alloy powder and silver-palladium mixed powder) can significantly improve the material's resistance to silver migration and improve sintering and mechanical properties. These advantages are directly related to the long-term reliability of electronic components in high humidity, high voltage, or high temperature environments. Furthermore, silver-palladium alloy powder, through uniform mixing at the atomic level, fundamentally optimizes the material's performance. It solves the inherent shortcomings of traditional mixed powders, such as easy runaway during sintering and easy silver migration during use, thus becoming an ideal choice for manufacturing high-end electronic components such as multilayer ceramic capacitors (MLCCs) and low-temperature co-fired ceramics (LTCCs).

[0003] Currently, the publicly available preparation methods yield mostly spherical silver-palladium alloy powders. However, in conductive pastes, flake-shaped silver-palladium alloy powders typically exhibit lower resistance than spherical powders. The core reason lies in the fact that flake-shaped particles can form larger-area "surface contact" or "line contact" conductive paths, while spherical particles only have "point contact." This difference in contact method fundamentally determines the efficiency of electron transport and the final resistance. Therefore, the preparation of flake-shaped silver-palladium alloy powders is of great significance.

[0004] Currently, when preparing flake silver-palladium alloy powder, silver powder and palladium powder are usually mixed and then ball-milled. However, the flake silver-palladium alloy powder prepared by this method has high resistance, poor dispersibility, and extremely uneven alloying. It often requires complex heat treatment for further alloying before it can be used. Summary of the Invention

[0005] This invention provides a method for preparing low-resistivity flake-shaped silver-palladium alloy powder. The silver-palladium powder prepared by this invention has low resistance and good dispersibility.

[0006] This invention provides a method for preparing low-resistivity flake-shaped silver-palladium alloy powder, comprising the following steps: (1) A silver salt solution, a palladium salt solution, and a reducing agent solution are mixed to carry out a reduction reaction to obtain silver-palladium alloy powder; (2) The silver-palladium alloy powder, dispersion and ball milling dispersant are mixed and then ball milled to obtain flake silver-palladium alloy powder; The grinding balls used in the ball mill include one or more of steel balls, zirconium dioxide balls, and agate balls.

[0007] Preferably, in step (1), the mixed raw materials also include a dispersant.

[0008] Preferably, the total mass ratio of the silver salt and palladium salt to the dispersant is 1:0.01~0.5; The dispersant includes one or more of polyvinylpyrrolidone, gum arabic, and polyethylene glycol.

[0009] Preferably, the total mass ratio of the silver salt and palladium salt to the reducing agent is 74.5:20~50; The reducing agent includes one or more of ascorbic acid, hydrazine hydrate, and glucose.

[0010] Preferably, the reduction reaction is carried out at a temperature of 15~60℃ for a time of 0.5~5h.

[0011] Preferably, the dispersion comprises one or more of water, ethanol, and triethanolamine; the mass ratio of the silver-palladium alloy powder to the dispersion is 1:2~10.

[0012] Preferably, the ball milling dispersant comprises one or more of cetyl alcohol, oleic acid, polyethylene glycol, and polyvinylpyrrolidone; The mass ratio of the silver-palladium alloy powder to the ball milling dispersant is 1:0.001~0.008.

[0013] Preferably, the mass ratio of the silver-palladium alloy powder to the grinding balls is 1:1 to 10; The ball milling speed is 100~500 r / min, and the time is 1~8 h.

[0014] Preferably, after ball milling, the process further includes washing, drying, and grinding the resulting ball-milled product.

[0015] The present invention also provides a conductive paste, characterized in that it comprises low-resistivity sheet-like silver-palladium alloy powder, glass powder, metal oxide and organic carrier prepared by the preparation method described above.

[0016] This invention employs a "first alloy, then ball milling" method to prepare flake-shaped silver-palladium alloy powder. This approach independently optimizes the two key steps of "alloying" and "flake formation," thereby improving the uniformity and morphology controllability of the powder at the atomic level. This contrasts sharply with the "mechanical alloying" method (directly mixing silver and palladium powders and ball milling), which couples alloying and flake formation together. While this strategy decouples the complex process and adds more steps, it results in precise control over the product's composition, structure, and final performance. The prepared flake-shaped silver-palladium alloy powder exhibits good dispersibility, a smooth surface, and superior resistivity compared to spherical alloy powder, spherical mixed powder, and flake mixed powder. This is precisely why it meets the stringent requirements of high-end electronic components (such as MLCCs and precision thick-film circuits).

[0017] In the process of preparing flake silver-palladium alloy powder by ball milling, the ball milling dispersant is the core process component that determines the success or failure: it plays three key roles at the same time as a lubricant (anti-welding agent), a morphology guide (controlling the aspect ratio), and a stabilizer (anti-agglomeration agent). In the subsequent slurry sintering process, the dispersant can be removed by high-temperature sintering without affecting the resistivity of the slurry. Attached Figure Description

[0018] Figure 1 SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 1; Figure 2 The energy spectrum of the flake-shaped silver-palladium alloy powder prepared in Example 1; Figure 3 SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 2; Figure 4 SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 3; Figure 5 SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 4; Figure 6 SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 5; Figure 7 SEM image of the spherical silver-palladium alloy powder prepared in Comparative Example 1; Figure 8 SEM image of the spherical silver-palladium mixed powder prepared in Comparative Example 2; Figure 9 SEM image of the flake-shaped silver-palladium mixed powder prepared in Comparative Example 3; Figure 10 SEM image of the spherical silver-palladium mixed powder prepared in Comparative Example 4; Figure 11 The image shows a SEM image of the silver-palladium alloy powder prepared in Comparative Example 5. Detailed Implementation

[0019] This invention provides a method for preparing low-resistivity flake-shaped silver-palladium alloy powder, comprising the following steps: (1) A silver salt solution, a palladium salt solution, and a reducing agent solution are mixed to carry out a reduction reaction to obtain silver-palladium alloy powder; (2) The silver-palladium alloy powder, dispersion and ball milling dispersant are mixed and then ball milled to obtain flake silver-palladium alloy powder; The grinding balls used in the ball mill include one or more of steel balls, zirconium dioxide balls, and agate balls.

[0020] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0021] This invention involves mixing a solution of silver salt, a solution of palladium salt, and a solution of a reducing agent to carry out a reduction reaction, thereby obtaining silver-palladium alloy powder.

[0022] In this invention, the mixing preferably includes mixing a solution of silver salt with a solution of palladium salt to obtain a silver-palladium mixed solution, and then adding a solution of reducing agent dropwise to the silver-palladium mixed solution.

[0023] In this invention, the preferred dripping rate is 5-100 mL / min. In specific embodiments of this invention, it can be 5 mL / min, 15 mL / min, 25 mL / min, 35 mL / min, 45 mL / min, 55 mL / min, 65 mL / min, 75 mL / min, 85 mL / min, 95 mL / min, or 100 mL / min. In this invention, the preferred method for preparing the silver salt solution includes dissolving the silver salt in water.

[0024] In this invention, the water preferably includes deionized water or ultrapure water.

[0025] In this invention, the concentration of silver salt in the solution is preferably 100~1100 g / L, and in specific embodiments of this invention, it can be 100 g / L, 200 g / L, 300 g / L, 400 g / L, 500 g / L, 600 g / L, 700 g / L, 800 g / L, 900 g / L, 1000 g / L, or 1100 g / L; the silver salt preferably includes silver nitrate.

[0026] In this invention, the volume ratio of the silver salt solution to the palladium salt solution is preferably 1:1.

[0027] The preferred method for preparing the palladium salt solution includes dissolving palladium in nitric acid; the concentration of the nitric acid is preferably 68 wt%.

[0028] In this invention, the palladium preferably comprises fine palladium powder or sponge palladium.

[0029] In this invention, the concentration of palladium salt in the solution is preferably 50-500 g / L, and in specific embodiments of this invention, it can be 50 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, 350 g / L, 400 g / L, 450 g / L, or 500 g / L; the palladium salt preferably includes palladium nitrate.

[0030] In this invention, the mass fraction of palladium salt in the silver-palladium mixture is preferably 8.7%; the mass ratio of silver salt to palladium salt is preferably 63:37.

[0031] In this invention, the concentration of the reducing agent in the solution is preferably 5~50 g / L, and in specific embodiments of this invention, it can be 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L or 45 g / L.

[0032] In this invention, the preparation of the reducing agent solution preferably includes dissolving the reducing agent in water to obtain the reducing agent solution.

[0033] In this invention, the total mass ratio of the silver salt and palladium salt to the reducing agent is 74.5:20~50. In specific embodiments of this invention, it can be 74.5:25, 74.5:30, 74.5:35, 74.5:40 or 74.5:45. The reducing agent preferably includes one or more of ascorbic acid, hydrazine hydrate and glucose.

[0034] In this invention, the mixing preferably includes: mixing a solution of silver salt, a solution of palladium salt and a dispersant to obtain a silver-palladium mixed solution, and adding a solution of reducing agent dropwise to the silver-palladium mixed solution.

[0035] In this invention, the mixed raw materials preferably further include a dispersant, which preferably includes one or more of polyvinylpyrrolidone, gum arabic, and polyethylene glycol.

[0036] In this invention, the mass ratio of the total mass of the silver salt and palladium salt to the mass of the dispersant is preferably 1:0.01~0.5, and in specific embodiments of this invention, it can be 1:0.03, 1:0.05, 1:0.1, 1:0.2, 1:0.3 or 1:0.4; In this invention, the temperature of the reduction reaction is preferably 15~60℃, and the time is preferably 0.5~5h. In specific embodiments of this invention, the temperature of the reduction reaction can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃ or 55℃, and the time can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.

[0037] In this invention, the reduction reaction is preferably carried out under stirring conditions, and the stirring rate is preferably 150~700 r / min. In specific embodiments of this invention, it can be 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, 650 r / min or 700 r / min.

[0038] After obtaining the silver-palladium alloy powder, the present invention mixes the silver-palladium alloy powder, the dispersion liquid and the ball milling dispersant and then ball mills them to obtain flake-shaped silver-palladium alloy powder.

[0039] In this invention, the mass ratio of the silver-palladium alloy powder to the dispersion is 1:2 to 10. In specific embodiments of this invention, it can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10. The dispersion preferably includes one or more of water, ethanol and triethanolamine.

[0040] In this invention, the preferred mass ratio of the silver-palladium alloy powder to the ball milling dispersant is 1:0.001~0.008. In specific embodiments, this ratio can be 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007, or 1:0.008. The ball milling dispersant preferably includes one or more of cetyl alcohol, oleic acid, polyethylene glycol, and polyvinylpyrrolidone. In the ball milling process for preparing flake silver-palladium alloy powder, the ball milling dispersant is a crucial component determining success: it simultaneously plays three key roles: lubricant (anti-welding), morphology guide (controlling aspect ratio), and stabilizer (preventing agglomeration). During the subsequent slurry sintering process, the dispersant can be removed by high-temperature sintering without affecting the slurry's resistivity. In this invention, the grinding balls used in the ball mill preferably include one or more of steel balls, zirconium dioxide balls, and agate balls; the mass ratio of the silver-palladium alloy powder to the grinding balls is preferably 1:1 to 10, and in specific embodiments of this invention, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10.

[0041] In this invention, the ball milling speed is preferably 100-500 r / min, and the time is preferably 1-8 h. In specific embodiments of this invention, the ball milling speed can be 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, or 500 r / min, and the ball milling time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h.

[0042] After ball milling, the present invention preferably further includes washing, drying and grinding the obtained ball-milled product.

[0043] In this invention, the washing method preferably includes centrifugal washing and / or natural sedimentation washing.

[0044] In this invention, the drying temperature is preferably 40~80℃, and in specific embodiments of this invention, it can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.

[0045] In this invention, the grinding is preferably carried out at room temperature (25°C).

[0046] The present invention also provides a conductive paste comprising low-resistivity sheet-like silver-palladium alloy powder, glass powder, metal oxide and organic carrier prepared by the preparation method described above.

[0047] In this invention, the mass fraction of low-resistivity flake silver-palladium alloy powder in the conductive paste is preferably 75%.

[0048] In this invention, the mass fraction of glass powder in the conductive paste is preferably 2%; the mass ratio of Bi2O3, B2O3 and SiO2 in the glass powder is preferably 35:20:45.

[0049] In this invention, the mass fraction of metal oxide in the conductive paste is preferably 3%, and the mass ratio of CuO to ZnO in the metal oxide is preferably 85:15.

[0050] In this invention, the mass fraction of glass powder in the conductive paste is preferably 20%, and the mass ratio of ethyl cellulose to terpineol in the organic carrier is preferably 15:85.

[0051] The following detailed description of the preparation method of the low-resistivity sheet-like silver-palladium alloy powder and the conductive paste provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1 Weigh 55.12g of silver nitrate and dissolve it in 150mL of deionized water to obtain a silver nitrate solution; Weigh 15g of palladium and dissolve it in 150mL of 68wt% nitric acid to obtain palladium nitrate solution; Mix silver nitrate solution and palladium nitrate solution, add 2.5g of polyvinylpyrrolidone and mix well to obtain silver-palladium mixture.

[0053] Weigh 30g of ascorbic acid and dissolve it in 2000mL of water to obtain a reducing agent solution; The reducing agent solution was added dropwise to the silver-palladium mixture, and the reaction was carried out at 25°C with magnetic stirring for 50 minutes. The product was then washed to obtain silver-palladium alloy powder.

[0054] 50g of the silver-palladium alloy powder, 100g of water, 100g of ethanol, 0.1g of cetyl alcohol, and 50g of steel balls were placed in a ball mill jar and ball milled at room temperature (25°C), a ball milling speed of 150r / min, and a ball milling time of 4h. The powder was then washed and dried (65°C) to obtain the flake-shaped silver-palladium alloy powder.

[0055] Example 2 The difference from Example 1 is that the ball milling dispersant is oleic acid.

[0056] Example 3 The difference from Example 1 is that the ball milling dispersant is polyethylene glycol.

[0057] Example 4 The difference from Example 1 is that the ball milling time is 6 hours.

[0058] Example 5 The difference from Example 1 is that the ball milling speed is 250 r / min.

[0059] Comparative Example 1 Weigh 55.12g of silver nitrate and dissolve it in 150mL of deionized water to obtain a silver nitrate solution; Weigh 15g of palladium and dissolve it in 150mL of 68wt% nitric acid to obtain palladium nitrate solution; Mix silver nitrate solution and palladium nitrate solution, add 2.5g of polyvinylpyrrolidone and mix well to obtain silver-palladium mixture.

[0060] Weigh 30g of ascorbic acid and dissolve it in 2000mL of water to obtain a reducing agent solution; The reducing agent solution was added dropwise to the silver-palladium mixture, and the reaction was carried out at 25°C with magnetic stirring for 50 minutes. The product was then washed and dried (at 65°C) to obtain spherical silver-palladium alloy powder.

[0061] Comparative Example 2 Weigh 55.12g of silver nitrate and dissolve it in 200mL of deionized water. Add 1.25g of polyvinylpyrrolidone to obtain a silver nitrate solution. Weigh 10g of ascorbic acid and dissolve it in 1000mL of water to obtain a reducing agent solution. Add the silver nitrate solution dropwise to the reducing agent solution and react for 0.5h to obtain spherical silver powder.

[0062] Weigh 15g of palladium and dissolve it in 150mL of 68wt% nitric acid. Add 1.25g of polyvinylpyrrolidone to obtain a palladium nitrate solution. Weigh 20g of ascorbic acid and dissolve it in 1000mL of water to obtain a reducing agent solution. Add the palladium nitrate solution dropwise to the reducing agent solution and react for 0.5h to obtain spherical palladium powder.

[0063] The resulting spherical silver powder and spherical palladium powder are ground and mixed to obtain spherical silver-palladium mixed powder.

[0064] Comparative Example 3 50g of the spherical silver-palladium mixture obtained in Comparative Example 2, 100g of water, 100g of ethanol, 0.1g of polyvinylpyrrolidone, and 50g of steel balls were placed into a ball mill jar and ball milled at room temperature (25℃), a ball milling speed of 150r / min, and a ball milling time of 4h. The powder was then dried (65℃) and sieved to obtain the flake-shaped silver-palladium mixture.

[0065] Comparative Example 4 The difference from Example 1 is that the grinding balls used in the ball milling process are nylon balls.

[0066] Comparative Example 5 The difference from Example 1 is that no ball milling dispersant is added during the ball milling process.

[0067] Performance testing (1) Figure 1 This is a SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 1. Figure 2 The energy spectrum of the flake-shaped silver-palladium alloy powder prepared in Example 1 is shown.

[0068] Depend on Figure 1 It can be seen that the powder prepared in Example 1 of the present invention has a flake shape, a smooth surface, and good dispersibility; from Figure 2 The energy spectrum shows that the elements in the powder are evenly distributed, indicating an alloy structure.

[0069] (2) Figure 3 This is a SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 2.

[0070] Depend on Figure 3 It can be seen that the powder prepared in Example 2 of the present invention is in the form of flakes, has a smooth surface, and good dispersibility.

[0071] (3) Figure 4This is a SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 3.

[0072] Depend on Figure 4 It can be seen that the powder prepared in Example 3 of the present invention is in the form of flakes, has a smooth surface, and good dispersibility.

[0073] (4) Figure 5 This is a SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 4.

[0074] Depend on Figure 5 It can be seen that the powder prepared in Example 4 of the present invention is in the form of flakes, has a smooth surface, and good dispersibility.

[0075] (5) Figure 6 This is a SEM image of the flake-shaped silver-palladium alloy powder prepared in Example 5.

[0076] Depend on Figure 6 It can be seen that the powder prepared in Example 5 of the present invention is in the shape of flakes, has a smooth surface, and good dispersibility.

[0077] (6) Figure 7 SEM image of the spherical silver-palladium alloy powder prepared in Comparative Example 1.

[0078] Depend on Figure 7 It can be seen that the powder prepared in Comparative Example 1 of the present invention is spherical particles, without irregular shapes such as flakes or dendrites.

[0079] (6) Figure 8 SEM image of the spherical silver-palladium mixed powder prepared in Comparative Example 2.

[0080] Depend on Figure 8 It can be seen that the powder prepared in Comparative Example 2 of the present invention is spherical particles, without irregular shapes such as flakes or dendrites.

[0081] (7) Figure 9 SEM image of the flake-shaped silver-palladium mixed powder prepared in Comparative Example 3.

[0082] Depend on Figure 9 It can be seen that the powder prepared in Comparative Example 3 of the present invention is in the form of flakes.

[0083] (8) Figure 10 SEM image of the spherical silver-palladium alloy powder prepared in Comparative Example 4.

[0084] Depend on Figure 10 It can be seen that when nylon is used as the grinding ball, the powder prepared in Comparative Example 4 of the present invention is still spherical.

[0085] (9) Figure 11 The image shows a SEM image of the silver-palladium alloy powder prepared in Comparative Example 5.

[0086] Depend on Figure 11It can be seen that when no ball milling dispersant is added during the ball milling process, the powder prepared by Comparative Example 5 of the present invention is agglomerated large lumps.

[0087] (10) According to the slurry formula: 75 wt% silver palladium powder, 2 wt% glass powder (Bi2O3+B2O3+SiO2, with a mass ratio of 35:20:45), 3 wt% metal oxide (CuO+ZnO, with a mass ratio of 85:15), and 20 wt% organic carrier (ethyl cellulose+terpineol, with a mass ratio of 15:85). The powders obtained from Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, 3, 4, and 5 were rolled into slurry, printed onto ceramic substrates, and sintered at 850°C. Resistance tests were then performed, and the measured resistances were 4.87 mΩ / □, 5.95 mΩ / □, 5.69 mΩ / □, 4.95 mΩ / □, 5.05 mΩ / □, 11.21 mΩ / □, 23.88 mΩ / □, 20.12 mΩ / □, 12.01 mΩ / □, and 25.21 mΩ / □, respectively. This indicates that the flake-shaped silver-palladium alloy powder has the lowest resistance.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing low-resistivity flake-shaped silver-palladium alloy powder, characterized in that, Includes the following steps: (1) A silver salt solution, a palladium salt solution, and a reducing agent solution are mixed to carry out a reduction reaction to obtain silver-palladium alloy powder; (2) The silver-palladium alloy powder, dispersion and ball milling dispersant are mixed and then ball milled to obtain flake silver-palladium alloy powder; The grinding balls used in the ball mill include one or more of steel balls, zirconium dioxide balls, and agate balls.

2. The preparation method according to claim 1, characterized in that, In step (1), the mixed raw materials also include a dispersant.

3. The preparation method according to claim 2, characterized in that, The total mass ratio of the silver salt and palladium salt to the dispersant is 1:0.01~0.5; The dispersant includes one or more of polyvinylpyrrolidone, gum arabic, and polyethylene glycol.

4. The preparation method according to claim 1, characterized in that, The total mass ratio of the silver salt and palladium salt to the reducing agent is 74.5:20~50; The reducing agent includes one or more of ascorbic acid, hydrazine hydrate, and glucose.

5. The preparation method according to claim 1, characterized in that, The reduction reaction is carried out at a temperature of 15~60℃ for a time of 0.5~5h.

6. The preparation method according to claim 1, characterized in that, The dispersion includes one or more of water, ethanol, and triethanolamine; the mass ratio of the silver-palladium alloy powder to the dispersion is 1:2~10.

7. The preparation method according to claim 1, characterized in that, The ball milling dispersant includes one or more of cetyl alcohol, oleic acid, polyethylene glycol, and polyvinylpyrrolidone; The mass ratio of the silver-palladium alloy powder to the ball milling dispersant is 1:0.001~0.

008.

8. The preparation method according to claim 1, characterized in that, The mass ratio of the silver-palladium alloy powder to the grinding ball is 1:1~10; The ball milling speed is 100~500 r / min, and the time is 1~8 h.

9. The preparation method according to claim 1, characterized in that, The process after ball milling also includes washing, drying, and grinding the resulting ball-milled product.

10. A conductive paste, characterized in that, It includes low-resistivity sheet-like silver-palladium alloy powder, glass powder, metal oxide and organic carrier prepared by the preparation method according to any one of claims 1 to 9.

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