Copper-filled anodized aluminum oxide a potential material for chip to chip bonding

The unique bonding between Cu and Cu will be reported. The material was prepared by filling metal Cu into isolated nano-holes of anodized aluminum oxide (AAO). Nano-Cu filaments were exposed from AAO surface. The electric conductivity appears only in the vertical direction along filled metal, and insulation property appears in the horizontal direction. Thermal conductivity of Cu-filled AAO is 20 times higher than organic resin called the under-fill. We have succeeded in Cu-Cu bonding by a Flip-chip bonder within 1 minute in the atmosphere.