Copper bump bonding with electroless metal cap on 3 dimensional stacked structure

CBB, the copper bump bonding process, can perform flip-chip bonding in 100 /spl mu/m pitch with a thin electroless metal cap on the surface, leading to interconnection of the copper through-hole electrodes on a 3D stacked structure. In this paper, the results of the technical studies on both the electroless plating process and the thermo-compressive bonding process are introduced, which are key technologies for expansion to interconnections with 20 /spl mu/m pitch to realize advanced 3D stacked structures.