Fine-grain silver powder and process for producing the same

Abstract

Fine-grain silver powder that has a grain size of minuteness not known in the prior art, exhibiting dispersion close to monodispersion with reduced grain aggregation. For obtaining the fine-grain silver powder, an aqueous solution of silver ammine complex (S1) is caused to flow through given flow channel (hereinafter referred to as 'first flow channel'). Second flow channel (b) is disposed so as to join the middle of the first flow channel (a), and an organic reducing agent optionally together with an additive (S2) is caused to flow through the second flow channel (b). At confluence (m) of the first flow channel (a) and the second flow channel (b), contact and mixing is carried out so as to effect reduction deposition. Thus, there is obtained fine-grain silver powder of such powder characteristics not known in the prior art that the average diameter of primary grain (DIA) obtained by an image analysis of scanning electron microscope images is 0.6 m or less (a), the crystallite diameter 10 nm or less (b) and the sintering initiation temperature 240 DEG C or below.

Description

technical field [0001] The invention relates to a microparticle silver powder and a method for manufacturing the microparticle silver powder. Background technique [0002] As described in Patent Document 1, in the conventional production of silver powder, a wet reduction process in which an aqueous silver ammonia complex solution is produced with silver nitrate solution and ammonia water and an organic reducing agent is added to the aqueous silver ammonia complex solution has been used. In recent years, these silver powders are mainly used in the formation of electrodes or circuits of chip parts, plasma display panels, and the like. [0003] Patent Document 1: JP-A-2001-107101 [0004] Therefore, in the above-mentioned electrodes and circuits, it is required to greatly reduce the size of the formed circuits and electrodes, and to increase the density and precision of wiring and to have high reliability. [0005] However, the average particle size D of the primary particle ...

AI Technical Summary

Problems solved by technology

However, in order to obtain silver powder with low caking property, in terms of production conditions, a reaction system with rapid reduction has to be adopted. As a result, although the crystallinity is low, only silver powder with obvious aggregation can be obtained.

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