Bonding Mechanism of Direct Bond Copper to Alumina Substrate

Cu-Cu_2O eutectic bonding of copper to AL_2O_3 was investigated. The highest peel strength was 11.5kg/cm for the specimen prepared at 1070℃ for 3h in nitrogen atmosphere. Oxygen promoted the wetting between copper and Al_2O_3 greatly. Cu[O] melt reacted with the alumina and formed a continuous CuAlO_2 layer, which enhanced the peel strength of the joint. On cooling, the solidification front moved from the solid copper towards alumina, and Cu_2O precipitated from the Cu[O] melt. When the solidification front met the CuALO_2 layer, liquid-aided reaction completed and a reliable bond was achieved between the copper and Al_2O_3 substrate.