Abstract: Direct copper-bonded alumina substrates were widely used in large-power applications. Cu-Cu₂O eutectic bonding of copper to Al₂O₃ was investigated in this paper. Oxygen was introduced by pre-oxidizing copper foil and it was shown that Cu-Cu₂O eutectic liquid promoted the bonding between copper and Al₂O₃ greatly. Chemical reaction happened at the solid-liquid interface and led to the formation of the binary oxide CuAlO₂, which can be observed when the specimen was prepared at 1070℃ for 60min.

Key words: direct bonded copper（DBC）, pre-oxidizing, interfacial product