Fine copper powder

PROBLEM TO BE SOLVED: To make usable a copper powder as a filler for an electric conductive ink suitable to form an ultra-fine writting pattern with an ink-jet system or the like. SOLUTION: In a fine granular copper powder, copper particles having both of a short diameter and a long diameter of less than 100 nm and applied an oxidizing-resistant treatment on the surface are individually dispersed. The fine granular copper can be obtained in such a way that in the case of reducing copper hydroxide in solution into metallic copper grains by using a reducing agent, hydrazine or a hydrazine compound is used as the reducing agent, and the amount of the reducing agent used is made to be over three times of the necessary theoretical equivalent to reduction of the whole copper hydroxide and the whole amount of the deducing agent is added within 5 min, and the reducing reaction is performed under existence of an antifoaming agent, and before and after or on the way of the reducing reaction, a surface-treating agent is added. COPYRIGHT: (C)2009,JPO&INPIT