Method for preparing flake silver powder with low bulk density

Abstract

The invention provides a method for preparing flake silver powder with low bulk density. The method comprises the following steps of reducing silver powder, i.e. adding pure water into a reaction container, and adding silver nitrate under a stirring condition to make the silver nitrate completely dissolved; adding a PH(Potential Of Hydrogen) value regulator, stirring, adding formaldehyde serving as a reducer to perform chemical reaction, washing the silver powder and drying; and ball-milling, i.e. weighing the silver powder, adding zirconia, filling in a ball-milling pot, adding a ball-milling solvent, a ball-milling aid and an emulsifier, ball-milling, sieving, washing by using a cleaning solvent, and drying to obtain the flake silver powder. The silver powder prepared in the reducing process by the method is not added with any dispersing agent, has low impurity content and high purity; and moreover, the technical process is simple, the ball-milling time is short, and the method is easily industrialized.

Description

technical field [0001] The invention relates to a method for preparing flake silver powder with low bulk density. Background technique [0002] Flake silver powder is widely used in electronic components such as carbon film potentiometer terminals, membrane switches and filters. The physical properties of flake silver powder are important factors affecting the conductivity of silver paste. When the particle size of the flaky silver powder reaches the submicron scale and the shape is bright flakes, the printing effect, uniformity and flatness of the electronic circuit are significantly improved, and the amount of precious metals can be saved by 30%-50 %. There are many preparation methods of flake silver powder, which are divided into chemical method and mechanical method. The chemical reduction method is to use a special reducing agent to directly reduce the silver salt into flaky silver powder without ball milling in the middle. The mechanical method is divided into dry...

AI Technical Summary

Problems solved by technology

However, the wet ball milling process control is more complicated

Disclosed a kind of preparation method of low porosity ratio flaky silver powder in the patent application document such as application number 200510011011.0, this method adopts wet method ball milling, after a dry method ball milling, its ball milling process is very complicated, it is difficult to control the flaky silver powder. quality of silver powder

In addition, the patent application document with application number 200810097801.9 discloses a preparation method of highly dispersible flake silver powder. The flake silver powder prepared by this method needs to be dispersed by ultrasonic dispersion and air flow to improve the dispersion performance of silver powder, but the prepared by this method The particle size distribution of silver powder is wide, and the sheet diameter is D 50 3-25μ㎡; the bulk density distribution is too wide, and the bulk density is 0.5-1.8 g / cm 3 , it is difficult to meet the requirements for the use of flake silver powder with low bulk density

Another patent application document with application number 200810231718.6 discloses a preparation method of flaky silver powder. The method is to use unsaturated fatty acid as a dispersant in the preparation process of the precursor silver powder and as a dispersant in the ball milling process, but the full text of the document is not included. The important index of bulk density of silver powder is not involved, so it is impossible to know the specific performance of flake silver powder prepared by this method