SummaryWe developed the conductive ink using silver (Ag) -copper (Cu) solid solution powder and investigated an ionic migration phenomenon of the conductive ink. The conductive ink is made by dispersing the powder in phenol resin. This powder has a shell structure. The Ag concentration at the surface of the powder is higher than an average Ag concentration in the bulk, and Ag concentration decreases toward inside of the powder. The Ag concentration of about 85 wt% in the Ag-rich phase dose not strongly depend on the average Ag concentration, and the thickness of Ag-rich phase increase with the average Ag concentration. Though this ink includes Ag, in which ionic migration occurs most easily, and Cu, which is oxidized easily, the migration occurrence of this ink including the powder with Ag of 5 wt% was similar to that of Cu conductive ink and Ag migration was not observed.