Method for preparing compact silver-coated copper powder by using one pot method

Abstract

The invention relates to a method for preparing compact silver-coated copper powder by using the one-pot method. The silver-coated copper powder is in a coated core-shell structure, a core layer is made of copper, and a shell layer is made of silver. The preparation method includes: adding ammoniacal copper solution prepared by copper sulfate into aqueous solution containing reducing agent and dispersing agent to obtain copper powder suspension; adding water-soluble organic chelating agent into the suspension containing copper powder; adding ammoniacal silver solution prepared by silver nitrate into the suspension containing the copper powder to enable silver ions and the copper powder to be in a displacement reaction; after the displacement reaction finishes, additionally adding a certain amount of weak reducing agent to restore residual silver ions into silver; and filtering, washing and drying to obtain silver-coated copper powder with different grain diameters of 0.8-5 micrometers. The obtained silver-coated copper powder is uniform in silver coating of the shell layer, compact, good in conductivity, high in high-temperature oxidation resistance, and capable of being used for preparation of various electrode slurry sintered in the air.

Description

technical field [0001] The invention relates to a method for preparing silver-coated copper powder, in particular to a method for preparing dense silver-coated copper powder in one pot. Background technique [0002] The rapid development of the electronic information industry has driven the development of electronic paste with ultra-fine metal powder as the main functional phase, and with the development of electronic components to miniaturization, precision, and multi-function, the demand for electronic paste The requirements for technical indicators are also getting higher and higher. Common ultrafine metal powders include silver powder, gold powder, palladium powder, nickel powder, aluminum powder, copper powder, etc. Among them, silver powder is widely used in electronic components because of its excellent comprehensive performance. Copper is cheap and has a volume resistivity similar to that of silver, but copper powder is easily oxidized during preparation and use, wh...

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Problems solved by technology

[0005] The patent with the notification number CN101244459B discloses a preparation method of electroless silver-plated copper powder modified by rare earth. The copper powder is cleaned, activated, sensitized and ultrasonically assisted before plating. The process is relatively complicated and the cost is high.

[0006] The patent with the notification number CN1300381C discloses a preparation method of conductive composite copper powder and composite copper conductor slurry. The method adopts the introduction of a reducing agent to reduce silver ions to silver and deposit them on the surface of copper powder to form a coating structure. Strong reducing agents such as formaldehyde and hydrazine hydrate make the reaction speed fast, and it is not easy to reduce the spontaneous nucleation and growth of silver, which reduces the use efficiency of silver.

[0007] The patent with the publication number CN101214547A changes the surface morphology and layout of micron-scale copper-silver particles through chemical reduction, so that it contains a nano-scale surface. Although the surface sintering or melting temperature is reduced, oxygen can easily pass through the surface during high-temperature sintering. Oxidize copper, in addition, the system does not use surfactants or ultrasonic dispersion assistance, the dispersion of the system is poor, and the collision between particles is easy to agglomerate during the preparation process, so that the product particle size distribution is wide

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