| 摘要 |
PROBLEM TO BE SOLVED: To provide good conductivity for a through hole part, improve soldering thermal resistance after moisture absorption, and prevent generation of conductivity failures due to thermal shock by constituting a dendritic copper powder and a binder resin having a specific average particle diameter and an apparent density. SOLUTION: A dendritic copper powder obtained by an electrolyte or the like in 1 to 25 micrometers in average particle size and 1.0 to 4.0g/cm<3> in apparent density and preferably a binder resin of 10 to 40wt.% with respect to the copper powder are composed. Due to this copper powder, since a contact area between the copper powders is large, the conductive resistance value is low, the surface is relatively hardly oxidized, and there is no jamming during screen printing. This blending quantity of the binder resin is suitable to contact between the copper powders, and in particular, use of resor-type phenol resin is preferable. As required, a solvent of glycol ether or the like, oxidation inhibitor, and dispersant or the like are added. This copper paste is heated and cured after being embedded in a through hole of a printed circuit board by screen printing. |
