| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively and easily obtain copper powder having good electric conductivity and sagging preventing effect by specifying the average major axis diameter and flattening ratio therein. SOLUTION: Granular fine copper powder of 3 to 5μm average grain size obtd. by subjecting dendrite electrolytic copper powder obtd. by an electrolytic method to crushing and pulverizing by a collision board system jet mill is dispersed in water to form into copper slurry. The inside of this copper slurry is added with a lubricant such as fatty acid salt (sodium oleate or the like), a dispersant or the like, which is introduced into a medium type stirring mill, and the fine copper powder is flattened. At this time, the feeding rate of the copper slurry desirably controlled to about 0.5 to 1.0 l/min in the case the volume is 1.4 l, as the medium type stirring mill, a bead mill is used, the diameter of the beads is controlled to about 0.3 to 1.0 mm and the operating time of the flattening is controlled to 30 min to 2 hr. In this way, the flat shaped fine copper powder having 4 to 10μm average major axis diameter and 2 to 20 flattening ratio is obtd. Desirably, the bulk density therein is 2 to 4 g/cm3, and the BET specific surface area is 0.4 to 1.5 m2/g.
|
