CN-122007411-A - High-conductivity flaky silver-coated copper powder and preparation method thereof

Abstract

The invention relates to the technical field of silver-coated copper powder, and specifically comprises the steps of preparing flake alloy copper powder, electroless nickel plating and electroless silver plating alloy. The invention expands the application boundary of the flaky silver-coated copper powder from the conventional low-temperature environment to the fields of automobile electronics, aerospace power supply modules, high-temperature sensors, high-end power electronics packaging and the like with strict requirements on stability. The silver-coated copper powder prepared by the method systematically solves the problem of high-temperature failure of the silver-coated copper powder by constructing a stepped protection system from the inside to the outside of the powder and matching with an inert process environment.

Inventors

• LI QI
• WANG ZEHAO

Assignees

• 杭州睿衡新材料科技发展有限公司

Dates

Publication Date

20260512

Application Date

20260325

Claims (10)

1. 1. The preparation method of the high-conductivity flaky silver-coated copper powder is characterized by comprising the following steps of: S1, preparing flaky alloy copper powder, mixing quantitative particle copper powder with trace aluminum powder and silicon powder, performing wet ball milling under the protection of inert gas, wherein the ball-material ratio is 10:1, the rotating speed is 360rpm, the milling time is 12 hours, and obtaining flaky copper powder with target flake diameter D50=8-10 mu m and thickness of 1.0-1.5 mu m; S2, chemically plating nickel, taking quantitative nitric acid, washing the etched flaky alloy copper powder with deionized water to be neutral for 40 seconds to obtain activated copper powder, preparing a plating solution from quantitative nickel sulfate, sodium hypophosphite, sodium citrate, lactic acid and thiourea, dispersing the activated copper powder into the plating solution at the temperature of 85 ℃, continuously stirring for 1 hour, adjusting the pH value to 9 with ammonia water in the stirring process, washing the solution with deionized water after filtering, dehydrating the solution with ethanol, and vacuum-drying the solution to obtain nickel-plated copper powder; S3, chemical silver plating alloy, taking quantitative silver nitrate, complexing agent, palladium chloride and dispersing agent to form solution A, taking reducing agent to be solution B, taking stabilizing agent to be solution C, pouring the solution B into the solution A to be uniformly mixed, slowly dripping the solution C into the solution A by using a pipetting gun to form alloy plating solution, adjusting pH to 11.5 by using dilute ammonia water in the process, adding nickel plating copper powder into the alloy plating solution, carrying out ultrasonic dispersion and mechanical stirring for 2-3 hours at the constant temperature of 30 ℃ in a water bath, and dehydrating and vacuum drying to obtain the high-conductivity flaky silver coated copper powder.
2. 2. The method of producing highly conductive flake silver-coated copper powder according to claim 1, wherein in step S1, the particle diameter D50=3 to 5. Mu.m, the aluminum powder content is 0.5wt.%, and the silicon powder content is 0.2wt.%.
3. 3. The method of claim 1, wherein in the step S1, the grinding medium is ethanol, and the low-temperature annealing is performed at 430 ℃ for 1.5 hours.
4. 4. The method of claim 1, wherein in the step S2, the concentration of nickel sulfate is 27g/L and the concentration of sodium hypophosphite is 30g/L.
5. 5. The method of claim 1, wherein in the step S2, the concentration of sodium citrate is 16g/L, the concentration of lactic acid is 18g/L, and the concentration of thiourea is 2mg/L.
6. 6. The method of claim 1, wherein in the step S3, the concentration of silver nitrate is 2g/L, the concentration of palladium chloride is 0.08g/L, the complexing agent is ammonia water, and the concentration is 80mL/L.
7. 7. The method for preparing high-conductivity sheet silver-coated copper powder according to claim 1, wherein in the step S3, the reducing agent is glucose or formaldehyde, the concentration is 10g/L when glucose is adopted, and the concentration is 6mL/L when formaldehyde is adopted.
8. 8. The method for preparing the high-conductivity flaky silver-coated copper powder according to claim 1, wherein in the step S3, the dispersing agent is polyvinylpyrrolidone, the concentration is 10g/L, the stabilizer is cerium nitrate or sodium thiosulfate, the concentration of cerium nitrate is 35mg/L, and the concentration of sodium thiosulfate is 2mg/L.
9. 9. A preparation method of high-conductivity flaky silver-coated copper powder is characterized in that the thickness of a silver alloy layer on the surface of the high-conductivity flaky silver-coated copper powder is 130-180nm, and the thickness of a total coating layer of nickel and silver alloy is 200-220nm.
10. 10. A high conductivity sheet silver-coated copper powder, characterized by being prepared by the method for preparing a high conductivity sheet silver-coated copper powder according to any one of claims 1 to 9.

Description

High-conductivity flaky silver-coated copper powder and preparation method thereof Technical Field The invention relates to the technical field of silver-coated copper powder, in particular to high-conductivity flaky silver-coated copper powder and a preparation method thereof. Background The silver-coated copper powder is a high-performance conductive material, takes copper powder as a core, uniformly coats a layer of silver on the surface, and perfectly combines the high conductivity of silver and the low cost advantage of copper. The structure design effectively solves the problem that pure copper powder is easy to oxidize, and simultaneously greatly reduces the material cost, so that the structure design becomes an ideal choice in the fields of conductive adhesive, conductive ink, electromagnetic shielding, 3D printing and the like in the electronic industry. The silver layer not only provides an excellent conductive path, but also enhances oxidation resistance and stability, and ensures the reliability of the material in long-term use. Therefore, the silver-coated copper powder is widely applied to the fields of electronic packaging, photovoltaic cells, 5G communication equipment, flexible electronics and the like, and is a key material for realizing the balance between high performance and low cost. The high-conductivity flaky silver-coated copper powder perfectly combines high conductivity, excellent electromagnetic shielding performance and cost effectiveness by virtue of the unique flaky structure and the silver coating layer, so that the high-conductivity flaky silver-coated copper powder has wide application in various high-tech fields. The main application scene of the high-performance electronic packaging and conductive adhesive comprises ‌ high-performance electronic packaging and conductive adhesive, ‌ Printed Circuit Board (PCB) conductive ink, ‌ electromagnetic shielding material, ‌ new energy battery electrode material, ‌ heat conduction and dissipation material and conductive coating. For example, chinese patent publication No. CN108817377B discloses a preparation method of conductive flaky silver-coated copper powder, which comprises the steps of cleaning and activating flaky copper powder, forming crystal points on the surface of the copper powder, fully coating the copper powder by silver deposition, cleaning the silver-coated copper powder with water, then with ethanol, and finally drying to obtain the conductive flaky silver-coated copper powder. Compared with the prior art, the silver-coated copper powder prepared by the method has the advantages that the content of the coated silver powder is very high, the silver-coated copper powder is uniformly coated, copper is not exposed in the air, the copper is not easy to oxidize, the conductivity is good, and the storage is stable. However, when the silver-coated copper powder is applied to ‌ heat conduction and radiation materials, new energy battery electrodes and other conditions which need to be used in a high-temperature state, the tolerance temperature of the silver-coated copper powder is low, the copper core is outwards diffused and oxidized through the defect of the silver layer, and the silver layer loses the protection property due to high-temperature recrystallization, aggregation or rupture. In order to solve the problems, the invention provides the high-conductivity flaky silver-coated copper powder and the preparation method thereof. Disclosure of Invention The invention aims to provide high-conductivity flaky silver-coated copper powder and a preparation method thereof, so as to solve the problems in the background technology. In order to solve the technical problems, the invention provides a preparation method of high-conductivity flaky silver-coated copper powder, which comprises the following steps: S1, preparing flaky alloy copper powder, mixing quantitative particle copper powder with trace aluminum powder and silicon powder, performing wet ball milling under the protection of inert gas, wherein the ball-material ratio is 10:1, the rotating speed is 360rpm, the milling time is 12 hours, and obtaining flaky copper powder with target flake diameter D50=8-10 mu m and thickness of 1.0-1.5 mu m; S2, chemically plating nickel, taking quantitative nitric acid, washing the etched flaky alloy copper powder with deionized water to be neutral for 40 seconds to obtain activated copper powder, preparing a plating solution from quantitative nickel sulfate, sodium hypophosphite, sodium citrate, lactic acid and thiourea, dispersing the activated copper powder into the plating solution at the temperature of 85 ℃, continuously stirring for 1 hour, adjusting the pH value to 9 with ammonia water in the stirring process, washing the solution with deionized water after filtering, dehydrating the solution with ethanol, and vacuum-drying the solution to obtain nickel-plated copper powder; S3, chemical silver plating alloy, taking quantitativ