Method for preparing silver micro-powder for high-temperature sintering silver pastes

Abstract

The invention discloses a method for preparing silver micro-powder for high-temperature sintering silver pastes, which comprises the following steps: preparing a colloidal liquid silver system, a colloidal reduction system and protection solution firstly; then mixing the three. In the invention, a sol gel process and a solution chemical reduction method are used to effectively control the reaction process, so that the industrialized production can be performed stably, and the uniform reaction under the condition of production enlarging still can be ensured, thereby greatly improving the uniformities of shapes and other superficial characteristics of silver particles generated by reaction, and eventually generating flocculating soft silver powder wodges which are easy to carry out post-processing such as collecting and washing, and the like.

Description

technical field [0001] The invention relates to the preparation of functional silver micropowder, and the preparation method is suitable for industrial large-scale production of silver micropowder. The prepared silver micropowder can be matched and used in proportion to satisfy the preparation of electronic paste. Background technique [0002] Metal ultrafine powder itself has superior catalytic properties, magnetic properties, electrical properties, etc., so it has more and more applications in aerospace, atomic energy, electronics, powder metallurgy, chemical and other industries, as well as medicine and bioengineering. [0003] Among them, silver micropowder is widely used in the fields of electronics and electronic materials due to its excellent conductivity and application performance, and has an irreplaceable position in the electronics industry. Silver micropowder is mainly used in the preparation of conductive silver paste. The electronic silver paste series product...

AI Technical Summary

Problems solved by technology

This method is not conducive to the control of the particle size of silver powder, and high-speed centrifugation consumes a lot of energy, requires high equipment, solid-liquid separation and collection is difficult, and is difficult to meet industrialized mass production; the preparation method of the publication number CN1785558 adopts silver nitrate solution in the oxidation-reduction process. Add it dropwise to the reducing agent and dispersant, and adjust the pH value of the solution with ammonia water to prepare micron-sized silver powder, and obtain micron-sized spherical silver powder with different particle sizes of 0.1-3.0 μm

This method strengthens the stable control of the pH value in the reaction process, so that the whole preparation process is in a relatively stable and controllable range, which is conducive to scale-up production, but with the increase of batch production, this method has local reaction concentration and overall reaction. The concentration difference will continue to widen. Since the reaction nucleation process is a fast and instantaneous reaction (millisecond level), the concentration difference generated by the enlarged production will directly affect the uniformity of the silver powder.

Images