Preparation method of silver coated copper powder for electronic slurry

[0022] Example 1:

[0023] Weigh 10 grams of 500nm spherical copper powder raw material, add it into the reaction vessel, then add 200 ml of nitric acid with a mass concentration of 5%, ultrasonically stir for 5 minutes to remove oxides on the surface of the copper powder raw material, then filter and collect the filter residue, and use distilled water to clean the filter residue. 3 times to get the copper powder after pickling. Weigh 12 grams of EDTA and add it to 400 ml of deionized water to form a complex solution, then add the acid-washed copper powder into the complex solution, and stir evenly to obtain a reducing solution. Weigh 3 grams of silver nitrate into 150 ml of deionized water, then add 3 ml of ammonia water with a mass concentration of 28%, and stir to obtain a transparent silver ammonia solution. Under the dispersion and stirring of an ultrasonic disperser with a power of 500W, the silver ammonia solution was added to the reducing solution at a dropping rate of 0.05L/min to make it react. The reaction temperature was 35°C and the reaction time was 30min. After the reaction is completed, the reaction solution is filtered, the filter residue is collected, the filter residue is washed three times with deionized water, twice with anhydrous ethanol, and then vacuum dried at 50° C. to obtain silver-coated copper powder for electronic paste. After the silver-coated copper powder is prepared by the preparation method, no silver layer is found on the surface of the reaction vessel.

[0024] Example 2:

[0025] Weigh 52 grams of 800nm ​​spherical copper powder raw material, add it to the reaction vessel, then add 200 ml of sulfuric acid with a mass concentration of 5%, ultrasonically stir for 10 min to remove oxides on the surface of the copper powder raw material, then filter and collect the filter residue, and use distilled water to clean the filter residue. 3 times to get the copper powder after pickling. Weigh 74.43 grams of EDTA-2Na into 2000 ml of deionized water to form a complex solution, then add the acid-washed copper powder into the complex solution, and stir evenly to obtain a reducing solution. Weigh 31.4 grams of silver nitrate and add it to 600 milliliters of deionized water, then add 42.9 milliliters of ammonia water with a mass concentration of 25%, and stir to obtain a transparent silver ammonia solution. Under the dispersion and stirring of an ultrasonic disperser with a power of 300W, the silver ammonia solution was added to the reducing solution at a dropping rate of 0.05L/min to make it react. The reaction temperature was 40°C and the reaction time was 35min. After the reaction is completed, the reaction solution is filtered, the filter residue is collected, the filter residue is washed three times with deionized water, and then vacuum-dried at 60° C. to obtain a silver-coated copper powder for electronic paste. After the silver-coated copper powder is prepared by the preparation method, no silver layer is found on the surface of the reaction vessel.

[0026] Example 3:

[0027] Weigh 100 grams of 3um flake copper powder raw material, add it to the reaction vessel, then add 400 ml of formic acid with a mass concentration of 8%, ultrasonically stir for 15 min to remove oxides on the surface of the copper powder raw material, then filter and collect the filter residue, and the filter residue is subjected to distilled water. Wash 3 times to get pickled copper powder. Weigh 68.89 grams of EDTA and add it to 4000 ml of deionized water to form a complex solution, then add the acid-washed copper powder into the complex solution, and stir evenly to obtain a reducing solution. Weigh 33.05 g of silver nitrate and add it to 600 ml of deionized water, then add 45.1 ml of ammonia water with a mass concentration of 25%, and stir to obtain a transparent silver ammonia solution. Under the dispersion and stirring of an ultrasonic disperser with a power of 300W, the silver ammonia solution was added to the reducing solution at a dropping rate of 0.06L/min to make it react. The reaction temperature was 50°C and the reaction time was 45min. After the reaction is completed, the reaction solution is filtered, the filter residue is collected, the filter residue is cleaned with alcohol for 3 times, and then vacuum-dried at 50° C. to obtain the silver-coated copper powder for electronic paste. After the silver-coated copper powder is prepared by the preparation method, no silver layer is found on the surface of the reaction vessel.

[0028] The above examples illustrate that the preparation method of the silver-coated copper powder for electronic paste is not only suitable for small-scale laboratory preparation, but also for large-scale production.

[0029] The raw materials used in the examples, unless otherwise specified, are common commercially available industrial products.